Keir Starmer is travelling to the Gulf to meet leaders in the region to discuss diplomatic efforts to support the ceasefire agreed between the US and Iran.

The prime minister’s visit on Wednesday comes hours after a two-week ceasefire was agreed on Tuesday evening, canceling a self-imposed deadline by the US president, Donald Trump, for Iran to surrender or face widespread destruction.

Starmer said on Wednesday: “I welcome the ceasefire agreement reached overnight, which will bring a moment of relief to the region and the world.

“Together with our partners we must do all we can to support and sustain this ceasefire, turn it into a lasting agreement and reopen the strait of Hormuz.

Downing Street said the prime minister would discuss diplomatic efforts to support and uphold the ceasefire to bring a “lasting resolution” to the conflict, and protect the UK and global economy, which has squeezed consumers and countries around the world.

Starmer’s visit, planned before the ceasefire was announced, comes he faced mounting pressure to limit US access to British airbases, after Trump warned that a “whole civilization will die” if Tehran did not comply with his demands and allow commercial shipping to pass through the strait of Hormuz.

The US president’s comments were criticised from military observers and retired officers as “likely war crimes”, and were not directly criticised by Downing Street

The British foreign secretary, Yvette Cooper, is reported to have spoken with the US secretary of state, Marco Rubio, after Trump’s remarks and is said to have urged a swift end to the conflict, while giving the UK’s backing to negotiations and efforts to prevent further escalation.

Cooper and Rubio also discussed international efforts and diplomatic measures to open the strait of Hormuz, including a UK-led meeting chaired by Cooper that brought together more than 40 countries to pursue reopening.

The coalition of countries met in London last week to discuss possible economic and diplomatic measures to press Iran into opening the strait of Hormuz, a crucial oil and gas shipping route closed since US-Israel attacks began.