Iran's Supreme Leader Ayatollah Ali Khamenei attended a religious event on Saturday, according to a video carried by state media, in his first public appearance since the June 13 start of a 12-day war with Israel in which top Iranian commanders and nuclear scientists were killed.

US President Donald Trump repeated warnings to Khamenei throughout the war that his location was known and two unidentified US officials told Reuters Trump vetoed an Israeli plan to assassinate Iranian Supreme Leader Ali Khamenei.

Despite the alleged veto, Trump mused about killing Khamenei, then demanded Iran's "UNCONDITIONAL SURRENDER!"

Khamenei rejected US President Donald Trump's demand for unconditional surrender in a recorded speech played on television.

Americans "should know that any US military intervention will undoubtedly be accompanied by irreparable damage," he said. "Intelligent people who know Iran, the Iranian nation and its history will never speak to this nation in threatening language because the Iranian nation will not surrender."

This is a developing story.