Beirut: Hezbollah has appointed a successor to its senior commander Emad Mughnieh who was assassinated in Syria this week, a Lebanese security source said on Friday.

The source said the appointment was made hours after the announcement of Mughnieh's death in a car bomb in Damascus on Tuesday. He did not identify the successor who would now command Hezbollah's military wing.

A joint investigation into the bombing by Syrians, Iranians and Hezbollah was well under way and suspects had been arrested in the Syrian capital, the source said. The suspects were mostly Palestinians residing in Syria, the Lebanese source said.

Iranian Foreign Minister Manouchehr Mottaki agreed with Syrian officials during a visit to Damascus to set up a joint team to investigate the killing, Mottaki's deputy Alireza Shaikh-Attar said yesterday.

Hezbollah and its main backer Iran have accused Israel of killing Mughnieh. who was among the United States' most wanted men.

"A successor to Emad Mughnieh has been appointed, which is natural," said the source, who requested anonymity. "That's how Hezbollah works, they move quickly to choose successors of fallen leaders."

The source said the successor was not one of the two names being circulated in the Israeli media. Hezbollah leader Hassan Nasrallah has threatened Israel with "open war" in retaliation for the killing.

An Iranian Arabic television station released mobile phone footage of the scene minutes after the blast that killed Mughnieh.

It showed the car on fire and people running past it. The source said the investigation showed Mughnieh was killed by a car bomb parked close to his car.