Keir Starmer is chairing a meeting of the UK government’s Cobra emergency committee as Britain decides how to respond to the US-Israeli bombing of Iran, and Tehran’s retaliation against bases in the Gulf.

The UK did not participate in the first wave of strikes early on Saturday but had deployed RAF Typhoons to Qatar to protect the al-Udeid airbase in the country and other allied military facilities in the region.

British nationals in Bahrain, Kuwait, Qatar and the United Arab Emirates were advised to immediately shelter in place after reports of Iranian missile attacks. The Foreign Office advised against all travel to Israel and Palestine.

An extra six F-35s and additional air defence, radar and counterdrone systems were deployed to the RAF Akrotiri airbase in Cyprus, from where they could be deployed to defend Israel, Jordan or other countries in the Middle East.

It is understood British airbases were not used by the US air force as part of the attack; Starmer rejected a request from Donald Trump to use RAF bases in Diego Garcia and Fairford earlier this month.

Iran launched an immediate counterattack aimed at US bases in the Gulf, with initial reports of assaults on bases in Bahrain, Qatar, UAE and Kuwait, and at Israel. British forces are located at the bases in small numbers. There are no reports of any casualties.

The US and Israel appear to be engaging in a wide-ranging campaign aimed at regime change in Iran, as well as bombing its nuclear and missile sites. But in its initial statement, Britain would only say it did not want Tehran to have a nuclear weapon.

A government spokesperson said: “Iran must never be allowed to develop a nuclear weapon and that is why we have continually supported efforts to reach a negotiated solution. Our immediate priority is the safety of UK nationals in the region and we will provide them with consular assistance, available 24/7.

“As part of our longstanding commitments to the security of our allies in the Middle East, we have a range of defensive capabilities in the region, which we have recently bolstered. We stand ready to protect our interests.

“We do not want to see further escalation into a wider regional conflict.”

The chair of the foreign affairs select committee, Emily Thornberry, said the UK should resist being drawn into a conflict in the Middle East.

The Labour MP told BBC Radio 4’s Today programme she did not think the US-Israeli strikes were legal. “As far as I’m aware, we’re not involved in this,” she said. “There’s not been British agreement to be involved in this, and I think that’s the right thing to do. I don’t think that there’s a legal basis for this action.”

The US and Israel “were not under imminent threat, and so it’s therefore difficult to see what the legal justification is”.

Asked whether the UK should resist being drawn into the conflict, Thornberry said: “Absolutely, unless we’re attacked ourselves, which, as I say, unfortunately this morning, we don’t know whether we will be because there may be attacks by the Iranians on western bases in the Arab Gulf, and so then the situation may change. We just don’t know.”

The leader of the opposition, Kemi Badenoch, said she supported the US and Israeli attacks on Iran.

In a post on X, the Conservative leader said: “I stand with our allies in the US and Israel as they take on the threat of the Islamic Republic of Iran and its vile regime. The same regime that carries out attacks on the UK and on our citizens, that seeks to build nuclear weapons that would threaten our country and that brutally repressed pro-democracy protests only months ago and murdered thousands of its own people.

“Under my leadership, the Conservative party will always put our national security first and work with our allies to make the world a safer place.”