Investigators searched for clues Saturday amid the rubble of a car bombed building in a largely Christian neighborhood in Beirut (search), an attack that sparked fears of a renewed bloodshed in Lebanon and complicated already troubled negotiations between rival political groups over the formation of a new government.

The attack, which wounded nine people, came amid the withdrawal of Syrian troops to eastern Lebanon and Syria after a 29-year presence in this former civil war-ravaged country. The redeployments followed intense international and local opposition to Syria's role in Lebanon since the Feb. 14 assassination of ex-premier Rafik Hariri (search) in a massive bombing that killed 17 others.

The motive behind the attack wasn't immediately clear, but it devastated an eight-story residential building in Beirut's New Jdeideh (search) neighborhood shortly after midnight and sent panicked residents wearing pajamas and night gowns into the street to inspect the damage.

It also played to concerns among some Lebanese that pro-Syrian elements might resort to violence to show, in their view, the need for a continued presence by Damascus forces. Hundreds of thousands of Lebanese have been participating in demonstrations for and against Syria since Hariri was killed. Anti-Syrian opposition demonstrations have included large numbers of Maronite Christians.

"This has been the message to the Lebanese people for a while — to sow fear and terror among Lebanese citizens," Christian opposition member Pierre Gemayel (search) told Al-Jazeera satellite television. The message is "if there is a Syrian withdrawal from Lebanon, look what Lebanon will face."

Police closed all entrances leading to the blast site and blocked onlookers from nearing the devastated building. After sunrise, residents began clearing up debris and inspecting damage to their shops and homes in the area, sweeping broken glass and throwing out twisted metal and rocks thrown by the explosion.

In a statement released following the blast, Lebanon's pro-Syrian president, Emile Lahoud, made no mention of the attack, saying only that Lebanon was experiencing "exceptional circumstances" that required "immediate and direct dialogue" between opposition and pro-government groups.

Lahoud said Lebanon's various political factions must "shoulder their historic responsibilities in protecting the higher interests of Lebanon at this critical stage."

"The doors of the presidential palace will be open at any time to host such a meeting starting today," he said.

Political demands from factions for and against Syria have bogged down efforts to form a new government, raising concerns that the deadlock that could threaten upcoming elections and even Syria's final withdrawal.

Pro-Damascus premier-designate Omar Karami has insisted on a "national unity" government, but the anti-Syrian opposition is refusing to join before its demands are met. The opposition has demanded a neutral Cabinet to arrange for elections, the resignation of security chiefs and international investigation into Hariri's death.

Some opposition members accuse Karami of stalling to kill the chances of holding an election they believe the pro-Syrian camp will lose.

Walid Jumblatt, an opposition leader, said parliamentary elections should be held as planned for April and May.

"Why postpone the parliamentary elections? Let them hold the elections according to the electoral law they deem suitable, but we will not participate in the government," he told Future Television.

Saturday's explosion blew off the fronts of some structures, left a seven-foot-deep crater, damaged parked cars and shops and shattered windows for several blocks.

Witnesses said the car attempted to stop in front of a bingo hall, but security guards asked its driver to move along. The driver then parked the car a short way down the road. Minutes later it exploded.

"We were sleeping when it happened," said a white-haired man, wearing blue pajamas, who declined to be identified. "We don't know what and why. No one important lives here."

The intensity of the political battle over Syria's troops has raised fears of a return to the sectarian violence of the 1975-90 civil war. So far, however, the political camps do not conform to religious boundaries, with Christians and Muslims on both sides of the debate.

On Thursday, Syria completed the first phase of its withdrawal in Lebanon, redeploying all its remaining soldiers and military intelligence officers to the eastern Bekaa Valley. Of the 14,000 troops that were in Lebanon last month, at least 4,000 soldiers have returned to Syria.

At the United Nations, Maronite Cardinal Nasrallah Sfeir said that Syria had given assurances it would withdraw its troops before the country's elections, as U.N. and American officials want.