Syrian President Hafez al-Assad, a dominant figure in Middle East politics for over a quarter of a century, has died in Damascus at the age of 69.
The president's death was announced on Syrian television by a visibly upset presenter, who said it was a day of sorrow and pain in every house, school, factory and farm.
The Syrian parliament almost immediately amended the constitution to allow his son and heir, 34-year-old Bashar al-Assad, to succeed him as president - even though he is under the minimum age of 40.
President Assad's death comes at a critical time in the Middle East peace process, with Syria this week agreeing to work with the United States towards a revival of stalled talks with its rival Israel.
'Courage and vision'
The television statement said Mr Assad had "struggled for more than half a century for the sake of the Arabs' pride, unity, freedom, and for the sake of safeguarding their dignity and restoring their rights".
"His courage has never been weakened, his vision has never been narrowed, and his convictions have never been shaken."
Members of parliament were visibly distraught when they were informed of the news.
Shortly after the announcement of the president's death, crowds of people began to gather in the streets around Mr Assad's home in Damascus.
In the centre of the capital, hundreds of people demonstrated in support of Bashar al-Assad.
Reports said the late president's funeral would be held on Tuesday.
The Syrian Government has announced 40 days of official mourning for its leader. Flags will be flown at half-mast throughout the country, and in all Syrian embassies and diplomatic missions abroad.
The Lebanese President, Emile Lahoud, says he was the last person to talk to Mr Assad.
He has sent a telegram of condolence in which he says Mr Assad died while talking on the phone to him.
Correspondents say that in recent public appearances Mr Assad's walking had been stilted and his conversation slurred.
He had been in power since 1970. In November of that year, he led a peaceful coup, arresting and quietly imprisoning his political opponents.
Under his leadership, Syria was transformed into a major regional power.
President Assad was responsible for sending Syrian troops into Lebanon in 1976.
An implacable foe of Israel, he refused to hold negotiations with the Jewish state until the historic 1991 Arab-Israeli summit in Madrid.
But the Syrian track of the peace talks has always been the slowest moving, largely because of Mr Assad's cautious approach.
He tried to move closer to the West after the collapse of the Soviet Union and supported the allied coalition in the Gulf war against Iraq.
President Assad's death occurred only a week before the opening of a key conference of the ruling Ba'ath party.
Delegates had been expected to name Bashar al-Assad vice-president and a member of the party's regional command at the conference.