Iran’s Supreme Leader Ayatollah Ali Khamenei led the funeral prayers of Ismail Haniyeh and his bodyguard Wasim Abu Shaban. A large number of people attended the funeral prayer of the slain Hamas chief. He will be buried in Doha.

Ismail Haniyeh was assassinated in the early hours of the morning in Iran, the Palestinian militant group Hamas said on Wednesday, describing the strike as a "severe escalation" that would not achieve its goals.

Iran’s Revolutionary Guards confirmed the death of Haniyeh, hours after he attended a swearing-in ceremony for the country’s new president, and said it was investigating.

Also read: Hamas chief Ismail Haniyeh killed in Iran, Hamas says

There was no immediate comment from Israeli authorities. The White House did not immediately respond to a request for comment on Haniyeh.

"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."

Iranian Supreme Leader Ayatollah Khamenei said Iran will severely punish Israel for the martyrdom of Hamas chief Ismail Haniyeh in a missile attack on Iranian soil.

In a statement, the Iranian supreme leader said the criminal and terrorist Zionist regime has provided the grounds for harsh punishment for itself.

He stated avenging the blood of Ismail Haniyeh is Tehran’s duty, for he was martyred on Iranian soil.

He also expressed his condolences to the Muslim Ummah, Hamas, the Palestinian nation and the family of Ismail Haniyeh.