BORIS Johnson has said the UK will work to keep the Iran nuclear deal alive as leaders around the world criticised President Donald Trump’s decision to withdraw the US from the agreement.

The Foreign Secretary’s remarks came as Britain scrambled with key European allies to preserve the accord amid fears of a new confrontation in the Middle East.

Mr Johnson said the Government continued to believe the accord was “vital” to UK national security and had done its “utmost” to persuade Mr Trump not to abandon it.

He said it was up to the US to spell out the way forward and he urged the administration not to take any action which would hinder the efforts of the other parties to make it work.

“For as long as Iran abides by the agreement ... then Britain will remain a party. Britain has no intention of walking away,” he said.

Iranian President Hassan Rouhani responded with a warning of his own that his country could restart enriching uranium – a key element of a nuclear weapons programme – “without any limitations” within weeks. The speaker of the Iranian parliament, Ali Larijani, said there was now a window in which the EU could demonstrate whether it had the international clout to keep the agreement going.

French foreign minister Jean-Yves Le Drian insisted the deal was not dead and said the Europeans were prepared to work towards a wider accord which would address Mr Trump’s concerns. But with tensions already running high between Iran and Israel, he said the risks of a confrontation in the region were real.

UK Foreign Office Minister Alistair Burt sought to play down suggestions the US was ready to launch an attack on Iran – possibly using “proxies” such as the Israelis or the Saudis, who also remain highly suspicious of Tehran’s nuclear ambitions.

“We have no indication of anything like that,” he said.

Mr Burt acknowledged, however, that the president’s decision – despite appeals from Prime Minister Theresa May, French president Emmanuel Macron and German chancellor Angela Merkel – had shown the limits of European influence.

“On this issue he has not listened. That is absolutely correct. But now we have got to seek to persuade him and others there other ways of tackling the challenges he has set out,” he said.

Tensions over President Trump’s move grew as Mrs Merkel led a number of world leaders in expressing disappointment over the decision.

She said the US withdrawal showed Europe would face increasing responsibility to secure peace and seek political solutions to conflicts.

Mrs Merkel underlined the commitment of Germany, France and the UK to stick with the accord, telling members of her conservative party: “We have taken note with regret but also concern of this withdrawal by the United States of America, which is of course serious for such an agreement.”

China also expressed regret.

Foreign ministry spokesman Geng Shuang said that “ensuring the integrity and sanctity” of the agreement was important for upholding the international non-proliferation regime

Belgian prime minister Charles Michel said that instead of scuttling the nuclear deal with Iran, other countries should consider expanding economic relations instead.