UN Secretary General Ban Ki-Moon says he is sending a humanitarian team to northern Sri Lanka, where tens of thousands of civilians are trapped by fighting between government forces and cornered Tamil Tiger rebels.
Sri Lankan forces say they are providing aid to ethnic Tamils fleeing the violence
"The purpose of this humanitarian team will be to first of all monitor the situation and support the humanitarian assistance and try to do whatever we can to protect the civilian population," Ban told a press conference in Brussels.
Sri Lanka, however, rejected his appeal, saying that it was not sensible to send a mission to the war zone.
"We still estimate that about 50,000 remain there," said UN assistant secretary general for humanitarian affairs Catherine Bragg.
She told a press conference that some 95,000 people had already managed to reach the safety of refugee camps set up outside the conflict zone, although she stressed "all these are estimates, we don't have exact figures."
The Sri Lankan army has said some 15,000 to 20,000 civilians are still trapped in the narrow strip of land where the Tigers had been encircled by government forces.
Senior officers said the guerrillas from the Liberation Tigers of Tamil Eelam (LTTE) were confined to a mere 10-12 square kilometers of territory on the northeast coast of the Indian Ocean island.