Iran's Revolutionary Guards have said Israel killed Hamas political chief Ismail Haniyeh using a "short-range missile" fired from outside his Tehran compound.
They added that Israel was "supported by the United States of America" for the attack.
"This terrorist operation was carried out by launching a short-range missile," the statement said.
Haniyeh was killed on Wednesday in the Iranian capital.
Iran and Hamas have vowed to retaliate, the Guardian reported.
The Revolutionary Guards have reiterated that Israel will receive "a severe punishment at an appropriate time, place and manner".
