"Given the conducted investigations, the terrorist operation has been carried out through firing from outside the guests' residence a short-range projectile loaded with an almost 7 kg warhead, causing an intense explosion," the IRGC said on Saturday in its third statement about Haniyeh's assassination in an alleged Israeli attack in the Iranian capital Tehran, according to the armed force's official news outlet Sepah News.

The statement added the "terrorist" attack had been designed and carried out by Israel with the US government's support, Xinhua news agency reported.

The IRGC stressed that "the revenge for Haniyeh's blood will be definite," adding the "adventurist and terrorist" Israel would receive a "decisive response to this crime, which is a harsh punishment, at the appropriate time and place and with the appropriate quality".

Haniyeh, who had been invited to attend the swearing-in ceremony of Iranian President Masoud Pezeshkian on Tuesday, was killed along with his bodyguard early Wednesday when their residence in Tehran was hit.