In his strongest words yet, Pope Leo on Saturday denounced the “delusion of omnipotence” that is fuelling the US-Israel war on Iran and demanded political leaders stop and negotiate peace.

Leo presided over an evening prayer service in St Peter’s Basilica on the same day the US and Iran began face-to-face negotiations in Pakistan and as a fragile ceasefire held.

History’s first US-born pope did not mention the United States or President Donald Trump in his prayer, which was planned before the talks were announced. But Leo’s tone and message appeared directed at Trump and US officials, who have boasted of US military superiority and justified the war in religious terms.

“Enough of the idolatry of self and money!” Leo said. “Enough of the display of power! Enough of war!”

In the basilica pews was the archbishop of Tehran, Belgian Cardinal Dominique Joseph Mathieu. The US was represented in the diplomatic corps by its deputy chief of mission, Laura Hochla, the US embassy said.

In the first weeks of the war, the Chicago-born Leo was initially reluctant to publicly condemn the violence and limited his comments to muted appeals for peace and dialogue.

But Leo stepped up his criticism starting on Palm Sunday. And this week, he said Trump’s threat to annihilate Iranian civilisation was “truly unacceptable” and called for dialogue to prevail.