BANDA ACEH, Indonesia -- Indonesia warned aid workers Sunday that separatist rebels have taken shelter in camps for survivors, while a burst of violence hit Sri Lanka, signaling a potential resurgence of long-simmering rebellions in both tsunami-hit countries that could hamper help for victims of the 2-week-old disaster.
Compounding the misery, tropical downpours complicated relief efforts already slowed by impassable roads and destroyed bridges. Tens of thousands of survivors living in little more than tents and the drenching rain underscored the need to quickly build permanent shelters.
Decades-old conflicts in Indonesia and Sri Lanka lay dormant in the first two weeks after the magnitude-9.0 earthquake and tsunami struck, killing more than 150,000 people in Asia and Africa. But now they threaten to reignite as aid workers poured into the region with emergency assistance, some traveling to areas where outsiders are almost never allowed.
The workers say they are being cautious but won't let concerns about the rebellions slow the flow of aid.
"We don't believe that aid workers are targets," said Joel Boutroue, head of the U.N. relief effort in Indonesia's troubled Aceh province.
Ethnic tensions overshadowed U.N. Secretary-General Kofi Annan's tour of devastated areas in Sri Lanka. Hundreds protested in Sri Lanka's Tamil-dominated north after he acceded to a government request not to visit areas under rebel control.
"I'm hoping to come back and be able to visit all areas of the country, not only those repaired, but also to celebrate peace," Annan said before heading to the Maldives. "The U.N. is not here to take sides."
A rare burst of violence between Christians and Hindus in eastern Sri Lanka, where a massive aid effort is underway, revived security fears for relief workers there. At least three people were killed and 37 injured.
The Indonesian government warning offered no details about the infiltration into survivor camps, but came hours after police in the provincial capital, Banda Aceh, blamed separatists for nighttime gunfire close to the main U.N. compound in town.
Local military spokesman Ahmad Yani Basuki told the state-run Antara news agency that volunteers must understand that Aceh "is not like other regions in Indonesia."
"This is still a conflict-torn region," he said.
Indonesian authorities blamed separatist rebels for the shooting incident, near the house of a provincial police official. But the government routinely blames the rebels for violence -- even without evidence.
"We were told by guards that it was probably one person shooting a few rounds and that was it," Boutroue said.
The rebels have waged a separatist war in Aceh for nearly three decades in a conflict that has killed thousands.
An unofficial truce settled in after the Dec. 26 disaster, but recent skirmishes have prompted Indonesia's military to step up patrols for the guerrillas.
Security concerns have also been heightened by the appearance of Laskar Mujahidin, an extremist group with alleged links to al-Qaida. The group has set up an aid camp, but says it only wants to help and won't target foreigners.
Still, the aid effort continued unabated, with the World Food Program sending 170 staffers. Other agencies have similar numbers.
The U.S. military, with hundreds of personnel on ships near Sumatra and in Sri Lanka, said aid workers must be on guard in restive areas.
"Security is a constant planning factor in all that we do," U.S. Army aid coordinator Maj. Nelson Chang said.
Refugee camps are being built on Sumatra to house and feed half a million homeless people. Bodies are still being pulled from the rubble and buried in mass graves.
Rain pounded relief workers Sunday, turning Banda Aceh airport -- the hub for aid supplies -- into a muddy mess and soaking piles of cardboard boxes of supplies sitting on the tarmac. Scores of tents where aid workers and soldiers camped became a quagmire.
Despite the troubles, Mike Huggins, a World Food Program spokesman said help was getting to people in need.
"We are moving more food now than ever before and we're getting it further afield," he said. Aid officials said they may have to feed as many as 2 million survivors a day for six months.
Australia and Germany, among other countries, have led the way in pledging nearly $4 billion in aid -- the biggest relief package ever. President Bush called America's $350 million only an "initial commitment" and essentially a line of credit that can be spent as aid officials identify needs.
UNICEF chief Carol Bellamy, speaking on CBS television's "Face the Nation," continued warning about the fate of children.
"There has been in the past in this region, even before this horrible tragedy, criminal trafficking syndicates, trafficking young people, children, largely for sex purposes. There has been one case so far identified in Indonesia: people have been taken into custody by the government police authorities," she said, adding that most talk of child abuse and abduction so far are "rumors" about what "could happen."
Associated Press reporters Mike Corder and Beth Gardiner in Jakarta, Chris Brummitt and Denis Gray in Banda Aceh, Burt Herman off the coast of Sumatra, and Dilip Ganguly in Sri Lanka contributed to this report.