Gunmen in Lebanon have killed Maronite Christian leader Pierre Gemayel near Beirut.
Gemayel, 34, was the fifth anti-Syrian figure to be killed in the past two years and the first member of the government of Prime Minister Fuad Saniora to be killed.
Security sources said the attackers opened fire on Pierre Gemayel, a Maronite Christian leader, as his convoy drove through the Christian Sin el-Fil neighbourhood. Mr Gemayel, who was a strong critic of Syria, died of his wounds in hospital.
Local television footage showed angry and weeping supporters gathering at the hospital.
The assassination threatens further instability in Lebanon at a time when Hezbollah and other parties allied with Syria are planning large-scale street protests unless Saniora reforms his government to give them more power.
Pierre Gemayel
Damascus' opponents in Lebanon have accused Syria of being behind previous assassinations, particularly that of former Prime Minister Rafik Hariri, who was killed in a massive explosion in downtown Beirut in February 2005. Syria has denied any role.
Saad Hariri, Rafik's son and leader of the anti-Syrian parliamentary majority, broke off a televised news conference after hearing Gemayel had been shot.
In an interview with CNN, Hariri praised him as "a friend, a brother to all of us" and appeared to break down after saying: "We will bring justice to all those who killed him."
Hariri implicitly blamed Damascus for the assassination, saying, "We believe the hand of Syria is all over the place."
However, Syria also condemned the killing. "This despicable crime aims to destroy stability and peace in Lebanon," the state news agency said, affirming Syria's support for stability, security and unity.
Ahmed Mlli, a member of Hezbollah, speaking to al-Jazeera television also condemned the attack. "We strongly condemn and denounce this killing. It was carried out by those forces who want to harm the future of Lebanon," he said.
In Washington, the State Department denounced the assassination as terrorism and an attempt to intimidate Saniora's government. The United States has accused Syria and Iran of plotting to overthrow the government.
"We are shocked by this assassination," Undersecretary of State Nicholas Burns told reporters. He said it is very important that those who would use violence to divide Lebanon not be allowed to succeed. "We will give full support to the Saniora government in the days and weeks ahead," Burns said.
British Prime Minister Tony Blair condemned the killing and said it "underlines once again the absolute and urgent need for a strategy for the whole of the Middle East that supports those who favor democracy and the proper way of resolving disputes everywhere."
Israeli Foreign Affairs Minister Tzipi Livni said: "The news from Lebanon is another example of the kind of region, the kind of neighborhood we are living in."
Pierre Gemayel was a rising star in the party and expected to carry the mantle of the political family. His father, Amin, served as president between 1982 and 1988. His grandfather, the late Pierre Gemayel, led the right-wing Christian Phalange Party that fielded the largest Christian militia during the 1975-90 civil war between Christians and Muslims.
Amin Gemayel was elected by parliament after the assassination of his brother, Bashir, who was chosen president but was killed a few days before he was to take office.
The younger Pierre Gemayel was a prominent figure in Lebanon's anti-Syrian bloc, which dominates Saniora's Cabinet and the parliament - and which is now locked in a power struggle with the Muslim Shiite Hezbollah and its allies.
On Sunday, Hezbollah leader Sheik Hassan Nasrallah threatened a wave of street protests aimed at bringing down the government if it ignores the group's demand to form a national unity Cabinet, in which Hezbollah and its allies would have considerable influence and would be able to block major decisions.
Nasrallah accused Saniora's government of falling under the influence of the Bush administration and called it "illegitimate" and "unconstitutional."
Gemayel's assassination was the first since Gibran Tueni, prominent anti-Syrian newspaper editor and lawmaker, was killed in a car bomb in December. In June 2005, the journalist and activist Samir Kassir and former Communist Party leader George Hawi were killed in separate car bombings.