ISLAMABAD/TEL AVIV, April 8 - Mediation efforts to halt the war in Iran were hours from collapse when Pakistan mounted an overnight diplomatic push to secure a temporary ceasefire and bring Washington and Tehran into direct negotiations, four Pakistani sources told Reuters.

The effort nearly unravelled after an Iranian strike on a Saudi petrochemical facility triggered fury in Riyadh and threatened to derail weeks of back-channel diplomacy, the sources - with direct knowledge of the talks - said.

With a deadline set by U.S. President Donald Trump looming, Pakistani officials mounted a last-ditch attempt to pass messages between Tehran and Washington, after Trump warned that continued fighting that night could wipe out "a whole civilization."

Pakistan's effort involved direct contact with top officials across all sides, including Trump, Vice President JD Vance and U.S. special envoy Steve Witkoff, as well as Iranian Foreign Minister Abbas Araqchi and senior Revolutionary Guards commander Ahmad Vahidi, one of the sources said.

After what a second source described as several "intense, breathless" hours during which "the talks were almost dead", Iran agreed to a temporary ceasefire without preconditions and to enter negotiations.

"In the evening, Iran was on thin ice after the attacks on KSA (Saudi Arabia) but they knew there would be no extension to the deadline," the first source said.

Pakistan's military and civilian leadership remained engaged through the night, speaking to senior U.S. and Iranian, Saudi and other officials until Trump announced the breakthrough.

Minutes before Trump posted the announcement, he was on the phone with Pakistan's army chief, Field Marshal Asim Munir, the source said.

ASSURANCES ON ISRAEL

While Pakistan conveyed its "strongest ever anger" to Iran over the strike on Saudi Arabia, with whom Islamabad has a mutual defence pact that could drag it into the war, it simultaneously sought assurances from Washington that it would rein in Israeli strikes on Iran.