Colombo - Civilians caught in fighting between government forces and Tamil rebels in northern Sri Lanka were 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, running out of places to flee to, 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.

In Colombo, the office of the International Committee of the Red Cross (ICRC) was stoned by a group of protestors who were chanting slogans against the organization, for their recent comments made about the plight of civilians in the conflict zone.

The protestors claimed that the ICRC was backing the Tamil rebels and was making statements in favour of the LTTE.

The incident came hours after a pro-government lawmaker called on the expulsion of the head of the ICRC in Colombo, Paul Castella.

Wimal Weerawansa, the leader of the National Freedom Front (NFF) told a news conference that his party was demanding the removal of the ICRC head on the grounds that the organization was "acting as the LTTE's medical team and not as neutral party in the humanitarian crisis".

An ICRC spokesperson reacting to the comments said the ICRC remains in the conflict areas to carry out humanitarian assistance with the agreement of the government.

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 now 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 6,500 .

He said the last Tiger sea base located on the north eastern coast had been completely overrun by the military on Friday the Chalai area.

"The LTTE has no more bases of their sea Tiger (naval) unit". We have destroyed all of them," he said.

He said the rebels were now restricted to some 170 square kilometres adding that "all army units are now using a single map to carry out their operations as they have
(been) encircled now".

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)