A multipronged peace deal to reopen the strait of Hormuz within four days of sanctions being lifted and for the Houthis to withdraw substantial forces inside Yemen are at the heart of Gulf states’ plans to avert what they regard as a disastrous renewal of war between Iran and the US.

The US is aware of the talks’ progress but is holding out for a concession that European powers suggest could involve Iran allowing UN weapons inspectors back into the country.

The British foreign secretary, Ed Miliband, urged the Iranians to agree to readmit the UN weapons inspectors when he met the Iranian foreign minister, Abbas Araghchi, in New York but so far Iran has refused, saying it will only hold talks in principle on its nuclear programme.

European diplomats believe allowing weapons inspectors to reenter Iran and visit its bombed nuclear sites is a minimum requirement for a breakthrough with the US president, Donald Trump.

But Iran remains focused solely on the guarantees of sanctions relief it would receive in…