Colombo - Civilians caught in fighting between government forces and Tamil rebels in northern Sri Lanka are fleeing further into rebel-held areas on Friday as President Mahinda Rajapaksa assured the UN on the safety of civilians.

Dr T. Sathyamoorthy, based in a makeshift hospital in the conflict zone, who was speaking by telephone, said that civilians were now moving towards the coastal areas.

"We can hear the exchange of fire between the security forces and the LTTE (Liberation Tigers of Tamil Eelam)," said the doctor, who is based in Udayarakattukulam,
360 kilometres north-east of the capital Colombo.

On Thursday, Rajapaksa in a telephone conversation with UN Secretary General Ban ki-moon said the current military operations "would be carried out without harassment to the civilian population in the north," a statement from the president's office said.

The assurance was given when Ban visited in New Delhi. "The UN Secretary General was also told that the Sri Lankan security forces were compelled to carry out a humanitarian operation against a brutal terrorist organization, as the government considered the freeing of the Tamil people from the suffering they were undergoing under the forces of terror as its responsibility", the statement said.

Some 250,000 civilians are trapped in the conflict zone according to aid agencies, but government estimates say the figure is only around 150,000.

The rebel-held areas are limited to less than 250 square kilometres as more LTTE-controlled areas were captured by government forces.

On Friday 320 civilians entered government-controlled areas while 1,637 people did so on Thursday, military spokesman Brigadier Udaya Nanayakkara said, bringing the total number of civilians leaving rebel territory since January 1 to 5,000.

Local and international aid organizations called for a temporary halt in operations to enable civilians to escape, but the government has ruled out a truce and wants the LTTE to respond to a call to allow civilians to leave.

The military launched operations to recapture rebel-held areas in August 2006. (dpa)