AN EXPANDING fleet of ageing gas carriers engaging in unsafe and deceptive behaviour is racking up an alarming number of port state control detentions as it delivers record amounts of sanctioned Iranian gas.

Lloyd’s List’s analysis of vessel-movement data, cargo and satellite data has tracked more than 100 liquified petroleum gas carriers totalling over 5.1m cu m in carrying capacity suspected of carrying billions of dollars’ worth of Iranian LPG.

This comes as the Trump administration’s “maximum pressure 2.0” campaign against Iran gets underway, with US officials vowing to dramatically slash Iran’s oil exports.

While the dark fleet* of oil tankers moving sanctioned energy commodities from Russia, Iran, and Venezuela has been a topic of intense focus for the shipping industry and US sanctions authorities in recent years, the fleet of shadow LPG carriers ferrying propane and butane — both highly flammable in gaseous form — has flown below the radar despite posing similar safety, environmental, and regulatory risks.

The ‘shadow’ LPG fleet** tracked by Lloyd’s List includes vessels that either engaged in automatic identification system manipulation in the Middle East Gulf — typically done to obfuscate loadings of Iranian LPG — or suspected of loading Iranian LPG through ship-to-ship transfers (some VLGCs tracked to be taking Iranian LPG have themselves not engaged in AIS manipulation but have taken cargoes from VLGCs that did). About half of the vessels on the list appear in leaked documents from Iranian dissident website WikiIran showing they either called in Iran or had taken Iranian cargoes via STS.

The inherent dangers posed by the fleet were evident in October 2024, when VLGC Captain Nikolas (IMO: 9008108) and lightering vessel B- LPG Sophia (IMO: 9175846) caught fire during a ship-to-ship transfer of a suspected Iranian LPG cargo off Bangladesh. Both vessels were inspected by PSC authorities in 2024 and found to have fire safety-related deficiencies, although the findings of a Bangladeshi committee that investigated the October blaze have not yet been made public.

Further illustrating the fleet’s dubious safety record is its detention rap sheet. While it comprises roughly 10.5% of the global fleet by carrying capacity, vessels in the shadow LPG fleet accounted for over half of the 67 detentions of LPG carriers since January 2024, an analysis of Lloyd’s List Intelligence data showed.

Unsurprisingly, the fleet’s top flag states ranked poorly in the latest Paris Memorandum of Understanding on Port State Control report, which covered flag state’s performance in inspections between 2021-2023.

Panama, which was ranked in the bottom half of the Paris MoU grey list, is the largest flag state in the shadow LPG fleet, accounting for 36.4% of all carrying capacity. This is despite a months-long crackdown on its sanction-busting vessels that began early last year and has seen it purge much of its problematic tonnage.

Palau — which was ranked in the MoU’s black list — accounts for 11.7% of the shadow LPG fleet, and the flag of 11.6% of the fleet is unknown. Gambia, a relative newcomer to the flagging business, is the fleet’s fourth-largest flag state, and Cameroon, ranked at the bottom of the Paris MoU black list, is the fifth-largest. Gambia was not ranked in the latest MoU reports.

Contributing to the fleet’s risk profile is its advanced age. While LPG carriers can work safely for longer than oil tankers, it is unlikely that an oil and gas major would charter an LPG carrier of more than 20 years of age.

The average age of vessels in the shadow LPG fleet is 26, with the oldest gas carrier being the US-sanctioned VLGC Hai Ma (IMO: 8519966), built in 1987. That title was held until August 2023 by small gas carrier White Purl (IMO: 7230666), which caught fire off Assaluyeh, Iran, at the tender age of 51.

Fixed-premium providers lead the way

Insurance for about 54.5% of the fleet by number of vessels, including all 21 US-sanctioned LPG carriers, is unknown. Roughly 35% are entered with fixed-premium providers, while insurers that are part of the International Group of P&I clubs provide coverage for 10.6% of the fleet. Excluding US-sanctioned tonnage from the list — insurance for which is unknown — fixed-premium provider's share rises to 44%. 

However, sanctions exclusions clauses, which are standard practice in club rulebooks and insurance contracts, retroactively cancel coverage if a vessel is involved in illicit activity at the time an otherwise covered event takes place. Such was the case with the veteran White Purl.

The gas tanker had its blue cards issued by Ingosstrakh, but the Russian insurer told Lloyd’s List at the time that the vessel could not have been covered because it was in Iranian waters at the time of the accident.

More scrutiny ahead?

Since sanctions were reimposed during the first Trump administration in 2018, Iran’s LPG exports enjoyed relatively less scrutiny from US enforcement agencies compared to its crude sector, perhaps because of LPG’s smaller share of the revenue Iran generates from energy exports.

However, the US increased scrutiny on the sector last year, with 14 of the 21 sanctioned LPG carriers blacklisted in 2024. Another VLGC was sanctioned by the US in January 2025 over its owners’ links to Russia.

With the Trump administration’s stated aim of slashing Iran’s energy exports, Tehran’s LPG sector may well receive more scrutiny in the months ahead.

According to energy consultancy Facts Global Energy, Iran exported approximately 11.5m tonnes of LPG in 2025, a slight increase from the 11.4m exported the year prior. The data includes a small percentage of land-based exports.

FGE’s Middle East managing director Iman Nasseri estimated those exports at about $6.3bn in revenue, compared to $6bn in 2024, although he caveated that these were rough estimates. He further estimated Iran’s exports of oil, condensates, products, and LPG, generated $61bn in 2024, a $4bn decrease year on year.

Potentially because of the lighter regulatory oversight and because it is easier to falsify the origin of LPG cargoes, efforts to hide these shipments are less elaborate compared to Iranian crude, resulting in more efficient supply chains.

For instance, an Iranian crude cargo exported on board a VLCC will likely undergo several ship-to-ship transfers before it is ultimately discharged onshore. In contrast, an LPG cargo exported on very large gas carriers will typically undertake one STS transfer at the most, and VLGCs also sail directly from Iran to their disport.

There are several older, flagless VLGCs that shuttle cargoes from Iranian ports like Assaluyeh for STS transfers off Dubai. Younger vessels, which are less likely to come under scrutiny from PSC inspectors, then take the cargoes to their final destinations.

Some of the STS transfers take place with both vessels broadcasting their location; in other instances, one of the vessels spoofs their AIS to obfuscate the transfer.

“Unlike crude, which often undergoes multiple, complex transfers to obscure its origin, Iranian LPG typically moves through one STS transfer in the Middle East Gulf before reaching its final destination, primarily China,” said Claire Jungman, chief of staff at US advocacy group United Against Nuclear Iran.

However, this efficiency makes them “an attractive target for enforcement efforts”, Jungman said.

According to FGE’s Nasseri, the impact of US sanctions will hinge on the extent Washington wants to “go in chasing barrels”, and whether the Chinese government on both the federal and local level pressures buyers to abandon Iranian commodities.

If the US cracks down on Iran’s energy sector in the spirit of the Stop Harbouring Iranian Petroleum act of 2024, it could slash Iran’s exports by 20-30%, Nasseri said.

However, if China phases out Iranian LPG — perhaps as part of a future US-China trade deal — it could have a “material impact and cut Iranian LPG exports down by 50%-75%”, Nasseri told Lloyd’s List.

While some evidence has emerged of Chinese operators growing warier of Iranian oil and LPG, including the Shandong Port Group ban on US-sanctioned tonnage, workarounds were quickly being configured to keep the flow of sanctioned energy commodities into China going.

Efforts to keep Iran’s LPG from flowing will likely have to go beyond designations of vessels and traders. Four VLGCs were blocked by the Office of Foreign Asset Control in April 2024, and an additional five were blocked in mid-August 2024. Vortexa data showed a steep decline in cargoes lifted by sanctioned VLGCs from August to September, but volumes have mostly rebounded since.

** Lloyd’s List analysed vessel-tracking data from Lloyd’s List Intelligence, satellite imagery from Planet Labs and the European Union’s Space Programme, cargo data from Vortexa, and leaked documents from dissident website WikiIran, to assemble the list, which includes vessels that manipulated their AIS in the Middle East Gulf (typically done to obfuscate loadings of Iranian LPG), vessels suspected of calling in Iran, and vessels suspected of loading Iranian LPG through STS transfers. The list stood at 103 vessels as of 26 February 2025 and includes two small gas carriers that were sanctioned in 2024 for shipping LPG to Syria.

* Lloyd’s List defines a tanker as part of the dark fleet if it is aged 15 years or over, anonymously owned and/or has a corporate structure designed to obfuscate beneficial ownership discovery, solely deployed in sanctioned oil trades, and engaged in one or more of the deceptive shipping practices outlined in US State Department guidance issued in May 2020. The figures exclude tankers tracked to government-controlled shipping entities such as Russia’s Sovcomflot, or Iran’s National Iranian Tanker Co.

Correction: an earlier version of this story stated that both Captain Nikolas and B-LPG Sophia were detained in PSC inspection in 2024, but only Captain Nikolas was detained. B-LPG Sophia was cited with 16 deficiencies in a PSC inspection in September, but was not detained.