Syrian peace talks in doubt amid bombing, fractured opposition A suicide bomber detonated a truck filled with propane tanks at a crowded military checkpoint in central Syria on Sunday, killing more than 30 people, most of them civilians, in the second such attack by fighters linked to al-Qaida in two days. The attack, which was reported both by the state-run news media and anti-government activists, shook the city of Hama, ignited dozens of cars and sent up a column of smoke visible for miles around. One activist said the secondary explosions of gas tanks bursting continued long after the initial blast. Activists said the Nusra Front, one of the two al-Qaeda affiliates fighting alongside the rebels who seek to topple President Bashar al-Assad, was responsible for the attack. The bombing followed a similar attack east of Damascus the day before that killed 16 soldiers, suggesting an increasing reliance on suicide attacks to try to break government strongholds that the rebels are unable to take by conventional means. But the high civilian toll Sunday worried anti-government activists, who said it could lead to tensions between rebels and their extremist allies. The rise of extremist groups, which many rebels accept as battlefield companions even while disagreeing with their ideology, is one of the major challenges to international efforts to push for a negotiated end to the civil war. More than 100,000 people have been killed in Syria in 2 1/2 years of conflict. For months, the United States, Russia, the UN and other major powers have been pushing for peace talks to be held in Geneva between the government and the opposition. But dates for the talks have been delayed repeatedly. On Sunday, the secretary-general of the Arab League, Nabil al-Araby, suggested to reporters in Cairo that a conference would be held in Geneva on Nov. 23. But the joint U.N.-Arab League envoy for the Syria conflict, Lakhdar Brahimi, said at the same news conference that dates had yet to be set. Brahimi said he would soon travel to Qatar and Turkey, which support the rebellion, and Iran, which backs Assad, as well as meet with U.S., Russian and other international officials before official dates could be set.