THE British navy has assisted a very large liquefied petroleum gas carrier through the Strait of Hormuz as transits continue after Iran seized Stena Impero in international waters.

BW Group’s Isle of Man-flagged carrier BW Elm made the passage on Tuesday, despite UK government guidance to avoid the route.

The 2007-built BW Elm is the first British vessel above 10,000 dwt seen to transit the passage since Stena Impero, a UK-flagged, Stena Bulk-owned product tanker, was seized by Islamic Revolutionary Guard Corps on July 19.

Lloyd’s List understands BW Elm was not provided with a direct escort but was “closely shadowed” by a British naval vessel.

The unofficial escort was likely to have been provided by the warship HMS Montrose which is operating in the area and previously thwarted one attack on the UK-flagged suezmax tanker British Heritage. It arrived too late to prevent Stena Impero being taken.

BW Elm is heading for the port of Mesaieed, Qatar, to load an LPG cargo.

The decision to make the transit was only taken last night in Singapore after a risk assessment was carried out and in close consultation with UK Maritime Trade Operations.

The transit through international waters in the Gulf of Oman lasted about four hours at more than 17 knots, vessel-tracking data shows.

BW Group has a second VLGC in ballast — BW Mindoro — and sailing for the Middle East Gulf region. It is unclear whether this vessel is also likely to make the same passage.

BW LPG confirmed the BW Elm had completed the Strait of Hormuz transit and was heading to its load port in Qatar.

“BW LPG follows developments in the Strait of Hormuz closely and have asked all of our vessels to proceed with additional vigilance and to follow all appropriate security protocols in place,” a spokesperson said. “BW is liaising closely with all relevant authorities such as flag, class, and insurers and we are operating at our highest security protocol.”

The Department for Transport in London this week took the unprecedented step of extending the security level for British-flagged shipping from Level 3 in Iranian waters to cover all of the Strait of Hormuz.

British foreign secretary Jeremy Hunt said he was “advising against all passage in Iranian waters, and, for the moment, in the entire Strait of Hormuz” for British-flagged vessels.

Level 3 signifies exceptional risk with a probable or imminent security incident.

After outlining the government’s intention to establish a European-led naval maritime mission, Mr Hunt told the UK parliament that British-flagged ships are also to be asked “to give the government notice of any intention to pass through the Strait of Hormuz to enable us to offer the best protection we can”.

Shipowners would then receive advice on the safest way to transit, which may involve travelling in a convoy.

Eight British-flagged vessels above 10,000 dwt including chemical tankers, boxships and another LPG carrier are at ports and effectively stranded in the Middle East Gulf.

Six are signalling they are at anchor, while boxship Iberian Express was sailing west from the port of Jebel Ali on Tuesday afternoon.

A very large crude carrier operated by BP Shipping, Atlantic Pioneer, diverted to Fujairah during the weekend and remains there at anchor.

BW Elm is classed by DNV GL with P&I insurance provided by UK Mutual Steam Ship Assurance Assoc (Bermuda), according to the Lloyd’s List Intelligence website.

The gas carrier is one of the 145 vessels beneficially owned by privately BW Group, held by the Sohmen-Pao family. Some 39 are flagged in the Isle of Man.

The company has 39 VLGCs and a further 19 liquefied natural gas carriers, data from Lloyd’s List Intelligence shows.

The UK Ministry of Defence did not respond to Lloyd’s List email and phone call seeking comment on the passage of BW Elm.