Hamas leader Ismail Haniyeh has been killed in Iran, the Palestinian militant group and Iran's elite Revolutionary Guards say.
A statement issued by Hamas mourned the death of Haniyeh, saying he was killed in "a treacherous Zionist raid on his residence in Tehran".
Hanieh attended Iran's new president's swearing in ceremony on Tuesday.
"Early this morning, the residence of Ismail Haniyeh in Tehran was struck, resulting in his and one of his body guards' martyrdom," the Revolutionary Guards said in a statement on Wednesday.
 "The cause is under investigation and will be announced soon," it said.
Hamas leader Ismail Haniyeh was killed in his Tehran home. (AP PHOTO)
No one immediately claimed responsibility but suspicion immediately fell on Israel, which has vowed to kill Haniyeh and other leaders of Hamas over the group's October 7 attack on Israel that killed 1200 people and saw some 250 others taken hostage.
Iranian state television reported on his death early on Wednesday and analysts immediately began blaming Israel for the attack.
Israel itself did not immediately comment but it often doesn't when it comes to assassination carried out by their Mossad intelligence agency.
Israel is suspected of running a years' long assassination campaign targeting Iranian nuclear scientists and others associated with its atomic program.
In its campaign since, Israel has killed more than 39,360 Palestinians and wounded more than 90,900, according to the Hamas run Gaza Health Ministry, whose count does not differentiate between civilians and combatants.
with AP