The UK is continuing to demand the release of Stena Bulk's seized tanker Stena Impero, but has admitted its inability to fully protect its other ships in the Middle East Gulf.
The 50,000-dwt Stena Impero (built 2018) was held by Iranian forces on Friday in retaliation for Gibraltar's detention of the 301,000-dwt VLCC Grace 1 (built 1997) after an alleged sanctions breach.
Following a meeting of the UK government's emergency Cobra committee on Monday, James Slack, a spokesman for prime minister Theresa May, said the UK has again demanded the release of Stena Impero.
"We do not seek confrontation with Iran but it is unacceptable and highly escalatory to seize a ship going about legitimate business through internationally recognised shipping lanes," he added.
Slack said the vessel was seized under “false and illegal pretences and the Iranians should release it and its crew immediately”.
He also said the country's navy does not have the capacity to escort every British ship in the region.
And he added that the US has not offered to help with naval protection.
"The high volume of ships moving through the Strait of Hormuz - up to 30 ships covering more than 100 nautical miles - makes it impossible to escort vessels individually," he said.
"We already work closely with international partners to ensure a co-ordinated effort to defend freedom of navigation; this includes sharing information on threats to shipping and offering mutual protection for each other’s vessels."
"The US has been discussing with a number of countries, including the UK, how we might deliver maritime security in the face of recent threats to shipping."
The prime minister continued to meet with senior ministers to discuss Iran.
UK foreign secretary Jeremy Hunt has spoken with his Iranian counterpart on Monday, Slack said. He emphasised the UK does not want an escalation of the situation.
The government is advising UK shipping to stay out of the Middle East Gulf.
International problem
David Balston, director of policy at the UK Chamber of Shipping, said Iran's actions don't just affect UK shipping.
"Whilst totally acknowledging that clearly this a UK issue, it is also an international issue," he told TradeWinds by phone on Monday.
"Number one, the Iranians have now flagrantly broken international regulations by diverting the ship from Omani waters into their own and detaining it – or hijacking it, if that’s not too strong a word.
"But also the ship itself is Swedish-owned, has a UK flag and a multinational crew so it is very, very much an international problem," he said.
The UK Chamber says there must be an international solution, not just a UK solution to rising tensions in the region.
"We would prefer a diplomatic solution, but of course if that has to be underpinned by a multinational military support then so be it," said Balston, who commanded three submarines during his 32-year career in the Royal Navy.
"Above all else we do want to try and de-escalate the situation and try and get things returned to normal. But first and foremost, we want the ship and the crew back safely."
Before joining the UK Chamber in 2010, Balston worked in the Cabinet Office as the Prime Minister’s adviser on the Trident nuclear deterrent programme.
