The United Nations says the long-standing conflict between separatist rebels and the Indonesian military is not hampering its aid efforts in the tsunami devastated region of Aceh, but acknowledges precautions are in place after gunfire broke out near its headquarters in the capital of Banda Aceh.

Automatic gunfire broke out early Sunday near the U.N. tsunami relief headquarters in Banda Aceh, injuring no one, but causing alarm to nearby residents.

The U.N. coordinator, Joel Boutroue, says despite the ongoing conflict between separatist rebels and the Indonesian military, the U.N. aid effort is not being hampered in the least.

He says he does not believe aid workers are in danger, and says the massive relief effort is running according to plan.

"We have entire cooperation of the authorities. We do not believe that relief workers are targets in any case, so I do not see at this stage any hampering of our movement," he said. "As for the incident [early Sunday morning], we were told by guards at the gate, probably one person sort of shooting a few rounds of ammunition, that was it."

The United Nations is leading an unprecedented humanitarian relief effort in Indonesia's Aceh Province, after a magnitude-nine earthquake triggered a massive tsunami in the Indian Ocean that killed more than 150,000 people in 12 countries, two-thirds of them in Aceh.

Until the tsunami hit, the oil- and gas-rich province has been under martial law and was off limits to all foreigners, including aid workers, non-governmental organizations, and journalists.

The rebel Free Aceh Movement, known as GAM, declared a ceasefire after the tsunami hit, but sporadic fighting has broken out in recent days causing concern to several relief organizations.

The U.N.'s Joel Boutroue says the United Nations is aware it is working in a conflict zone.

It has graded the capital, Banda Aceh, as a phase-three security threat and the rest of Banda Aceh as a phase four. The phases simply mean that outside the capital, U.N. workers cannot move without prior authorization, they cannot travel alone, or at night. A phase five is a complete U.N. withdrawal.

"So indeed there is some constraints for us we need to, I need to be given some notification and to approve these movements," explained Mr. Boutroue. "We are trying to indeed be cautious in our movement in recognition of the environment in which we are operating."

GAM has been fighting for independence since 1976 and human-rights groups have accused the Indonesian military and the rebels of carrying out human-rights violations against the civilian population.