"The leaders discussed the ongoing situation in the Middle East and the importance of reopening the Strait of Hormuz to end the disruption to global shipping, which is driving up costs worldwide," a Downing Street spokeswoman said in a statement.

On Saturday, Trump urged other countries such as China, France, Japan, South Korea and Britain to send warships to help the United States secure the strait.

Iran's military is effectively blocking the crucial waterway in retaliation for US-Israeli strikes, aiming to damage the world economy and pressure Washington as oil prices soar.

Starmer also "expressed his condolences for the American service personnel who have lost their lives during the conflict", the statement said.