The Palestinian terrorist organisation Hamas announced on Wednesday that its leader, Ismail Haniyeh, had been killed in Iran early on a Wednesday morning. The group described the strike as a "severe escalation" that would not accomplish its objectives.

Hours after Haniyeh attended the inauguration of the nation's new president, the Revolutionary Guards of Iran declared that an investigation was underway and confirmed Haniyeh's passing.

The Israeli government did not immediately respond.

The White House did not immediately respond to a request for comment on Haniyeh.

The news, which came less than 24 hours after Israel claimed to have killed the Hezbollah commander it said was behind a deadly strike in the Israeli-occupied Golan Heights, appears to set back chances of any imminent ceasefire agreement in Gaza.

"This assassination by the Israeli occupation of Brother Haniyeh is a grave escalation that aims to break the will of Hamas," senior Hamas official Sami Abu Zuhri told Reuters.

He said Hamas would continue the path it was following, adding: "We are confident of victory."

Haniyeh, normally based in Qatar, has been the face of the Palestinian group's international diplomacy as the war set off by the Hamas-led attack on Israel on Oct. 7 has raged in Gaza, where three of his sons were killed in an Israeli airstrike.

Appointed to the Hamas top job in 2017, Haniyeh has moved between Turkey and Qatar's capital Doha, escaping the travel curbs of the blockaded Gaza Strip and enabling him to act as a negotiator in ceasefire talks or to talk to Hamas' ally Iran.