Iranian state television said Mugniyah, a leader of the Lebanese Shiite militant group allied to Iran, was killed by a car bomb blast in Damascus, Syria late Tuesday night. Hizbullah officials confirmed his death, without giving details on where it happened, and also pointed fingers at Israel. Jerusalem has denied it had any role in the killing.
Syria's Interior Minister Brigadier-General Bassam Abdul-Majid confirmed Wednesday that the Damascus explosion killed Mugniyah, the state-run news agency SANA reported.
It was the first official comment from Syria since Tuesday night's explosion in the Damascus neighborhood of Kfar Sousse. The agency quoted Abdul-Majid as saying an investigation into the blast was under way.
The Syrian minister defined the assassination as "the cowardly act of terror which shortened the life of the Lebanese fighter. He did not say who Damascus believed was behind the killing.
"The ongoing investigation over the car bomb in the residential Kfar Sousse neighborhood last night has proven that it targeted Lebanese combatant Imad Mugniyah," SANA said, quoting Abdul-Majid.
Prime Minister Ehud Olmert's office released a statement refuted the accusations, saying that "Israel rejects the attempt by terrorist groups to attribute any involvement (to Israel) in this incident."
Iranian Foreign Ministry spokesman Mohammad Ali Hosseini expressed Iran's ''strong condemnation'' of the killing.
''This action is a clear result and example of organized state terrorism by the Zionist regime,'' he said, according to the state news agency IRNA. He called on the world to ''prevent the Zionist regime from taking these actions that are a clear violation of international law.''
Hosseini praised Mugniyah, 45, who was believed to have masterminded a string of attacks in the 1980s and 1990s that killed hundreds of Americans and targeted US, Israeli and Jewish interests in Lebanon and elsewhere. He was also on an FBI wanted list with a $25 million bounty on his head, equal to that the US has put for al-Qaeda leader Osama bin-Laden.
Hosseini called Mugniyah ''a golden page in the history of mankind's fight against the aggressive and occupying Zionists.''
Both Hizbullah and Amal, the two Shiite organizations in Lebanon, accused Israel of being behind the assassination.
Sheikh Hussein Fadlallah, Hizbullah's spiritual leader said Wednesday that "with Mugniyah's killing, the jihad way has lost one of the pillars in the fights against its enemies." The Amal movement condemned the assassination, calling on Lebanese citizens "to stick to national unity."
US welcomes death of 'cold-blooded killer'
Meanwhile Wednesday, the United States applauded the Mugniyah's killing.
"The world is a better place without this man in it. He was a cold-blooded killer, a mass murderer and a terrorist responsible for countless innocent lives lost," said State Department spokesman Sean McCormack. "One way or another he was brought to justice."
McCormack said he did not know who was responsible for the killing of Moughniyah.
He was implicated in the 1983 bombings of the US Embassy and US Marine and French peacekeeping barracks in Beirut, which killed over 350 people, as well as the 1992 bombing of the Israeli Embassy in Buenos Aires and the kidnapping of Westerners in Lebanon in the 1980s.
He was under indictment in the United States for his role in planning and participating in the June 14, 1985, hijacking of a US TWA airliner and the killing of an American passenger.
"This is somebody who was a mass murderer. He was a cold-blooded killer responsible for countless
deaths of many people from many nations," said McCormack.
"You can just go down the list of other nationalities that were affected by his acts of terror ... The list goes on and on and on," he added
Reuters and AP contributed to this report