A suspected leader of the Al-Qaeda network arrested in Lebanon last week over bomb plots against Western targets died on Monday from what security services said was a massive heart attack.
Lebanese national Ismail Mohammed al-Khatib, described as the top Al-Qaeda operative in the country, was among 10 people detained last week after security forces said they foiled a plot to blow up the Italian embassy in Beirut.
The announcement triggered anger in his hometown in Lebanon's Bekaa valley, where residents challenged the official version of his death and several hundred marched on a Lebanese border checkpoint, hurling stones and bottles.
"Khatib was taken ill in the morning and taken immediately to hospital but he died of a massive heart attack," according to a statement from the Lebanese security forces.
It said the cause of death of the man, said to be 31, was given by authorised medical examiners.
Lebanon's Interior Minister Elias Murr said when he announced the arrests last week that Khatib and his operatives were planning to pack a car with 300 kilograms (660 pounds) of TNT and ram it into the Italian embassy.
He said it was the first Al-Qaeda network to be uncovered and smashed in Lebanon, describing Khatib as "the head of an Al-Qaeda linked terrorist movement."
He said the network was also planning attacks against the Ukrainian embassy in Beirut. Both Italy and Ukraine are members of the US-led forces in Iraq.
Murr said the network also aimed to "recruit young fundamentalists to carry out operations against the coalition forces in Iraq".
Khatib was being detained in a secret location, although the hospital where he died, Dahr Al-Basheq, is situated in the north of Beirut.
In his hometown of Majdal Anjar in the Bekaa valley near the border with Syria, an area known as a fundamentalist Sunni Muslim region, feelings were running high as hundreds of people gathered outside Khatib's house.
"There is no God but God and the state is the enemy of God," a group chanted as they marched down the street towards a checkpoint on the Lebanon-Syria border, an AFP correspondent said.
Several hundred people began throwing stones and empty bottles at a Lebanese security post at the border, smashing windows, but an army patrol in the area did not intervene.
Protestors challenged the government's assertion that Khatib was an Al-Qaeda man, saying he was illiterate and didn't own a fax machine or a computer.
"Ismail was in good health so how could he die of a heart attack. They surely must have killed him," said one resident, who declined to be named.