BANDA ACEH, Indonesia -- A US helicopter on a relief operation crashed in a rice paddy near Banda Aceh's airport, injuring at least two US servicemen and causing the military to briefly suspend flights today, while strong aftershocks and security concerns provided more challenges for aid workers two weeks after the disaster hit.
The two men injured in the crash, along with eight other Navy personnel, were being flown back to their ship in the Lincoln battle group, said Captain Joe Plenzler, a US military spokesman in Medan, 250 miles southeast of Banda Aceh.
The SH60 helicopter crashed in a rice paddy about 500 yards from the airport in Banda Aceh, the main city on Indonesia's tsunami-battered Sumatra island, as it was trying to land, he said.
''There was no fireball but a little smoke. It landed on its side," Plenzler said, adding that the helicopter's propeller was twisted from the impact.
US authorities said there was no indication the helicopter had been shot down. The US military suspended helicopter flights for about two hours after the crash.
The crash occurred a day after Indonesia warned aid workers that separatist rebels have taken shelter in camps for survivors and 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 Dec. 26 disaster.
Relief workers straining to help survivors of the earthquake and tsunami that has killed more than 150,000 people across 11 countries and left millions homeless and threatened by disease said they were 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 UN relief effort in Indonesia's troubled Aceh Province.
Aftershocks from the massive earthquake that spawned the killer waves, meanwhile, continued to rattle residents in the hardest-hit countries. A 6.2-magnitude temblor sent people scrambling from their homes early today in Banda Aceh, but no injuries or damage were reported.
The Indonesian government warning offered no details about the infiltration into survivor camps, but was issued hours after police in the provincial capital, Banda Aceh, blamed separatists for nighttime gunfire close to the main UN 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.
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 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 Qaeda. 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, with the World Food Program sending 170 staff members. Other agencies have similar numbers.
The US 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," said Major Nelson Chang, US Army aid coordinator.
Aid officials said they may have to feed as many as 2 million survivors a day for six months.