Geneva - The humanitarian situation in north-eastern Sri Lanka has become "extremely grim," a senior United Nations official in the Asian country said Wednesday.

Gordon Wiess, the spokesman for the UN's operations in Sri Lanka warned that some 70,000 to 200,000 were trapped in a tiny enclave between a lagoon and the sea front, desperate for food, shelter and drinking water.

He said it was "unacceptable" that civilians were cut off from aid.

"There is virtually no humanitarian access to the enclave. Nothing like what is needed to sustain the population inside there," Wiess said in a telephone interview.

Conditions in the territory were "extremely overcrowded, squalid, they are very short of water, apparently short of food, certainly short of medications."

"We have not had any consistent food deliveries since December last year," Weiss said, noting there were "only sporadic deliveries of food supplies."

The parties to the conflict were "obliged to facilitate access, whether by evacuating civilians or opening the gates so humanitarian actors can have full, consistent, meaningful, substantive contact with the civilian population," Weiss said.

Furthermore, "there are big issues of humanitarian law at stake," owing to actions by both the Sri Lankan military as well as the Tamil Tiger rebels.

Both sides have been accused of rights violations, including causing harm to the civilian population. The rebels have been accused of not allowing the civilian population to flee.

The Sri Lanka military says it is close to defeating the rebels after years of war, since overtaking key rebel holds in recent weeks as part of a military campaign which was stepped up in 2006. (dpa)