The United Nations humanitarian chief John Holmes held talks with leaders in Sri Lanka on Thursday over the fate of thousands of civilians trapped in the island's war zone.
Holmes met with Foreign Minister Rohitha Bogollagama as the Tamil Tiger rebels stood on the brink of defeat at the hands of government troops after a bloody 37-year campaign for an independent Tamil homeland.
The UN has accused the Tigers of shooting civilians who try to escape from rebel-held territory, and has also pleaded with the military to avoid non-combatant casualties.
A foreign ministry official said Holmes was expected to travel to the northeast of the island to inspect government-run relief centres for those fleeing the conflict.
The visit came as the International Committee of the Red Cross reported an "unfolding catastrophe" with trapped civilians short of food, medicine and shelter.
Holmes, who last visited Sri Lanka in 2007, was also scheduled to discuss the humanitarian situation with aid groups during his three-day visit.
Sri Lanka's government on Wednesday rejected fresh calls for a truce as troops took another village from rebel control.
It has staunchly denied targeting civilians and accused the Tigers of fabricating reports of non-combatant deaths.
The Liberation Tigers of Tamil Eelam (LTTE) ended weeks of silence on Thursday with a statement saying more than 100 civilians had been killed in an air attack on Wednesday in an area still under their control.
"Many bodies remain buried in the bunkers and will take a while to be removed," the rebels said. "With extreme shortages of medicines and hospital facilities many more of the injured will die."