Thousands of mourners carried Khatib's white-shrouded body through the town before burying him on Wednesday, relatives angrily dismissed any al-Qaida link, and pointed to abrasions and bruises on the corpse that they said were signs of torture.
"He died under torture. He was given electric shocks, beaten with sticks and they put cigarettes out on his body," said al-Khatib's father Muhammad.
Lebanon's Interior Ministry said al-Khatib died of a heart attack on Monday, sparking a riot among residents of his hometown of Majdal Anjar that paralysed a nearby border crossing with Syria for several hours as they protested.
No official reaction
There was no immediate official reaction to those claims and virtually no official or state security presence at Khatib's funeral, where mourners carried banners blaming Interior
Minister Ilias al-Murr for the death and demanding he resign.
Family members say al-Khatib was
tortured to death
Lebanese officials said last week they had thwarted planned attacks on Italian and other foreign missions and Lebanese targets, and arrested a dozen suspects including Khatib, who they described as al-Qaida's top man in Lebanon.
The alleged plot was the most recent in a string that authorities claim to have foiled in Lebanon.
Judicial officials are preparing charges against other suspects in the alleged plot, which Lebanese authorities said had been foiled after a tip from Italian authorities and in cooperation with Syria's security services.
The arrests have provoked sceptical comment in Lebanon, where Syria earlier this month began to redeploy some of the thousands of its soldiers who Washington and a UN Security
Council resolution have demanded to leave the country.
That resolution came ahead of a constitutional change to keep Lebanon's pro-Syrian president in office which deputies said was secured by pressure from Syria's president and
intelligence officials in Lebanon.
Damascus flooded Lebanon with troops early in its 1975-1990 civil war and since the end of the war has consolidated its grip in Lebanon through broad influence over the presidency, army, security services and judiciary.