The Royal Navy has seized anti-tank missiles and fins for ballistic missiles during a raid on a small boat believed to be heading from Iran to Yemen.

The action in the Gulf of Oman comes after other seizures by French and US forces in the region as Western powers increase their pressure on Iran as it enriches uranium closer to weapons-grade levels.

Regional and international powers are also trying to agree an end to the years-long war gripping Yemen, the Arab world’s poorest country, and there is also criticism of Iran supplying arms to Russia for its war on Ukraine.

The raid took place on February 23 after an American aircraft detected a small boat heading from Iran, with a helicopter from the Royal Navy frigate HMS Lancaster giving chase to the vessel, the Ministry of Defence said.

The boat tried to re-enter Iranian territorial water but was stopped before it could.

Inside the boat, British troops found Russian 9M133 Kornet anti-tank guided missiles, known in Iran as Dehlavieh, the US Navy’s Middle East-based 5th Fleet and the Royal Navy said.

Those weapons have been seen in other seizures suspected to be from Iran and bound for Yemen.

Also on board were small fins that the US Navy identified as jet vanes for medium-range ballistic missiles.

Iranian components have helped build a missile arsenal for Yemen’s Houthi rebels, who have held the country’s capital, Sanaa, since 2014.

A United Nations resolution bans arms transfers to Houthi rebels. Tehran has denied arming the rebels despite physical evidence, numerous seizures and experts tying the weapons back to Iran.

“This seizure by HMS Lancaster and the permanent presence of the Royal Navy in the Gulf region supports our commitment to uphold international law and tackle activity that threatens peace and security around the world,” UK Defence Secretary Ben Wallace said.

Vice Admiral Brad Cooper, the commander of the American 5th Fleet, said this was the “seventh illegal weapon or drug interdiction in the last three months and yet another example of Iran’s increasing malign maritime activity across the region”.

The war in Yemen has deteriorated largely into a stalemate and spawned one of the world’s worst humanitarian crises. However, Saudi-led air strikes have not been recorded in Yemen since the kingdom began a ceasefire at the end of March 2022, according to the Yemen Data Project.

That ceasefire expired in October despite diplomatic efforts to renew it. That has led to fears the war could again escalate. More than 150,000 people have been killed in Yemen during the fighting, including over 14,500 civilians.