Hamas political chief Ismail Haniyeh was killed earlier this week by a “short-range projectile” launched from outside his residence in Tehran, Iran’s Islamic Revolutionary Guard Corps (IRGC) has said.

In a statement issued on Saturday, the IRGC said that based on investigations conducted so far, the attack against Haniyeh “was carried out by firing a short-range projectile carrying about 7kg [15.4lb] of explosive materials and launched from outside the guests residency”.

It added that Israel will receive “a harsh punishment in due time and place” for Haniyeh’s assassination, which, it said, was “supported by the criminal government” of the United States.

Israel has neither confirmed nor denied a role, while the US has said it “was not aware of or involved in” Haniyeh’s killing that threatens to plunge the Middle East into further conflict amid Israel’s relentless war on the Gaza Strip.

The Palestinian leader and his bodyguard were killed in an Iranian government guest house in Tehran in the early hours of Wednesday.

The head of Hamas’s political bureau had gone to the Iranian capital to attend the inauguration of Iran’s newly elected Masoud Pezeshkian.

On Friday, thousands of people attended Haniyeh’s funeral prayer at a mosque in Qatar’s capital, Doha, where the Hamas chief had lived along with members of the group’s political office.

His assassination came hours after top Hezbollah commander Fuad Shukr was killed in an Israeli air attack on a the southern suburbs of Lebanon’s capital, Beirut.