Banda Aceh, Indonesia ? Rebels in tsunami-devastated Aceh province accused the government of abandoning an informal cease-fire after the military said Friday it has killed scores of suspected guerrillas to protect aid deliveries.

The rebels disputed the military’s claim of killing 120 rebels in the past two weeks, saying only 20 of its fighters had died in skirmishes. The rebels said 100 others killed were unarmed civilians.

The renewed hostilities in the nearly three-decade separatist conflict called into question the security of efforts to aid survivors of the Dec. 26 tsunami. Tallies of the dead from the disaster have varied widely, from about 158,000 to 221,000 in 11 nations.

With as many as a million survivors in need of food and shelter, humanitarian groups said a U.S. military decision to begin pulling back from relief operations could disrupt the flow of aid.

“My gut feeling is that no, the civilian side isn’t ready to take over,” said Aine Fay, Indonesia director for the Irish aid group Concern. “The American military, the military hardware has been so useful.”

“I’m a bit taken aback that they’re thinking of withdrawing it already,” she said.

More than 11,000 U.S. troops and 16 Navy ships are providing relief support, according to the Pentagon. Since the operation began Jan. 1, they have delivered more than 8,600 tons of relief supplies to the affected region.

Indonesians living in aid camps were also worried about the withdrawal of American forces.

“I want them to stay here 100 percent. If they leave, there’ll be no more food,” said Mohamad Amin, a 50-year-old fisherman whose house was swept away by the waves.

Relief agencies have not reported any disruption to aid work by rebels. They have agreed to Indonesian requirements to register and travel with military escorts.

Nearly four weeks after the disaster, hundreds of delegates to a U.N. conference in Japan put the final touches on a pact Friday backing creation of a tsunami alert system to warn of cyclones, floods and other natural disasters.

But references in a planned final statement to global warming causing some natural disasters appeared likely to be removed after objections from the United States, Canada and Australia. The statement is expected to be signed when the conference ends today.