BEIRUT Hezbollah leader Imad Moughniyah, on the United States' most wanted list for attacks on Israeli and Western targets, has been killed by a bomb attack in Damascus, the Lebanese group said on Wednesday.
Hezbollah accused Israel of assassinating Moughniyah, who was head of the Hezbollah security network during Lebanon's 1975-90 civil war, by planting a bomb in his car. In Gaza, Hamas Islamists called for the Arab world to unite against Israel.
Israel denied any involvement in the killing, seen as a major setback to Syrian and Iranian-backed Hezbollah that fought a 34-day war with Israel in 2006.
Moughniyah, 45, was killed late on Tuesday. He had long been on a list of foreigners Israel wanted to kill or apprehend and the United States had offered a $5 million reward for his capture.
"His killing is a huge blow to Hezbollah. It is very indicative," Magnus Ranstrop, terrorism expert at the Swedish National Defence College, told Reuters.
Moughniyah was implicated in the 1983 bombings of the U.S. embassy and U.S. 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.
The United States indicted him for his role in planning and participating in the June 14, 1985, hijacking of a U.S. TWA airliner and the killing of an American passenger.
"For the U.S. administration Imad was the most wanted terrorist before Osama Bin Laden appeared. For many years, many different teams were looking for him, trying to exact the price for the catalogue of attacks he allegedly carried out," Ranstrop said.
"None of the (suspected) parties -- Israel and the United States -- will admit to it. The U.S. administration will celebrate. The Israelis will never claim responsibility. They make things happen."
Hezbollah, a strong political and military force in Lebanon, announced the assassination and called followers to his funeral on Thursday.
"After a life full of jihad, sacrifices and accomplishments ... Haj Imad Moughniyah ... died a martyr at the hands of the Israeli Zionists," said Hezbollah.
The 2006 war with Israel was triggered by a Hezbollah cross-border raid in which two Israeli soldiers were captured. According to Israeli intelligence assessments, Moughniyah was involved in masterminding the operation.
Israel also accuses Moughniyah of planning the 1994 bombing of a Jewish centre in Buenos Aires that killed 87 people and of involvement in a 1992 bombing of the Israeli embassy in the Argentine capital that killed 28.
"He was not only being targeted by Israel, but also by the Americans and many other parties," said former Mossad head Danny Yatom on Israel Radio. "He was one of the terrorists with the most amount of intelligence agencies and states chasing him."
Moughniyah had been a very tough target to track, he said, describing his death as a severe blow to Hezbollah.
"He behaved with extreme caution for many years. It was impossible even to obtain his picture. He never appeared or spoke before the media.
"His identity was hidden. His steps were hidden. He behaved with extreme caution, and that was the reason it was difficult to get to him for so many years."
The United States tried to detain Moughniyah several times, including a 1995 attempt to arrest him when the plane he was traveling was due to stop in Saudi Arabia. Diplomats said Saudi officials refused to allow the plane to land.
Syrian authorities had no comment on Tuesday's attack which took place in an upmarket district that houses an Iranian school, a police station and a Syrian intelligence office.
Witnesses at the scene told Reuters they saw security officers hauling the body away. Scores of police and intelligence officers rushed to the site. A police truck towed away the destroyed car, a new model Mitsubishi Pajero.
Senior Hamas officials, including leader Khaled Meshaal, live in exile in Damascus. At least one mid-level Hamas official has been killed in Damascus by a bomb attack in recent years.
Hamas blamed that attack on Israel.
"Israel rejects the attempts of terror elements to attribute to Israel any involvement in this incident," Prime Minister Ehud Olmert's office said in a statement.
Ranstrop said Moughniyah's killing was a signal to other leaders who live in Syria that they are not safe there.
Moughniyah was thought to be the commander of Islamic Jihad, a shadowy pro-Iranian group which emerged in Lebanon in the early 1980s and was believed linked to Hezbollah.
Islamic Jihad kidnapped several Western hostages, including Americans, in Beirut in the mid 1980s.
The group, which was founded in 1982, killed some of its captives and exchanged others for U.S. weapons to Iran in what was later known as the Iran-Contra scandal. Among those killed was the CIA's station chief.
Moughniyah's brother was killed in a car bomb in Beirut in 1994. Reports at the time suggested Imad had been the target. Moughniyah had spent much of the 1990s in Iran.
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(Additional reporting by Adam Entous and Ari Rabinovitch in Jerusalem; Writing by Tom Perry; Editing by Samia Nakhoul)