The strait and Iran’s nuclear issues were among the main points debated during 21 hours of talks in Islamabad, according to Iranian officials.

Those officials accused the US of making “excessive demands”, leaving a cloud of uncertainty over a two-week ceasefire struck on Tuesday.

When he emerged from the discussions on Sunday, US Vice-President J.D. Vance said the nuclear issue was a key sticking point.

Vance said Washington needed to see an “affirmative commitment” that Iran would not seek to develop nuclear weapons and would not seek the tools to build them quickly.