BEIRUT, Lebanon (AP) — Lebanese protesters erected flaming roadblocks and gunmen roamed the streets yesterday in a city on edge after the assassination of a top security official in a powerful car bomb the prime minister linked to the civil war in neighbouring Syria.

The crisis raised a terrifying spectre for Lebanese who fear their country could easily plunge back into cycles of violence and reprisal that have haunted it for decades.

Friday's blast in the heart of Beirut's Christian area killed eight people, including the country's intelligence chief, Brigadier General Wissam al-Hassan. It was the deadliest bombing in Beirut in four years, shattering the country's uneasy calm.

The government declared a national day of mourning for the victims yesterday, but protesters burned tyres and set up roadblocks in anger.

Sharbal Abdo, who lives in the neighbourhood where the bomb went off, brought his six-year-old son, Chris, and 12-year-old daughter, Jane, to see the destruction yesterday.

"They were very afraid yesterday," he said. "They need to face this situation. It may be their future."

Lebanese Prime Minister Najib Mikati yesterday linked the bombing to al-Hassan's high-profile investigation this summer that uncovered what authorities called a plot by Syria to provoke chaos in Lebanon with bombings and assassinations.

"I don't want to prejudge the investigation, but in fact we cannot separate yesterday's crime from the revelation of the explosions that could have happened," Mikati said at a news conference following an emergency Cabinet meeting.

Mikati, who opponents believe is too close to Syria and the Shiite militant group Hezbollah, offered to resign after the bombing, but was asked by President Michel Suleiman to stay.

Al-Hassan's probe led to the arrest of former Information Minister Michel Samaha, one of Assad's most loyal allies in Lebanon. Samaha, who is in custody, is accused of plotting a wave of attacks in Lebanon at Syria's behest. Indicted in absentia in the August sweep was Syrian Brigadier General Ali Mamlouk, one of Assad's highest aides.

Samaha's arrest was an embarrassing blow to Syria, which has long acted with impunity in Lebanon. Syria has powerful allies here, including the Shiite militant group Hezbollah, which now dominates the government.