UN pulls out of north Sri Lanka

The United Nations has pulled its staff out of Sri Lanka's rebel-held northern region after being ensured safe passage by government troops and rebels.

Other aid agencies have also left, after being prevented from doing so over the weekend by displaced people.

The agencies' move comes as the army continues a major offensive against the rebels in northern areas of the island.

The government ordered aid workers out of the north last week saying they could not guarantee their safety.

The army says it is closing in on rebel headquarters in Kilinochchi after other rebel bases fell in recent months.

KILINOCHCHI TOWN The capital of Kilinochchi District, it is part of the Northern Province of Sri Lanka Serves as the administrative centre and headquarters of the Tamil Tigers Rebels have their own judiciary and police force in the town According to the UN, 90% of population is Tamil Town surrounded by thousands of landmines, says the UN Town has high rates of infant mortality and malnutrition Government ordered aid agencies to leave, Sept 2008 Aid agency dilemma in Sri Lanka

Kilinochchi is the town where aid agencies in the north have been based.

A convoy of some 20 vehicles carrying UN and other staff set off from the town on Tuesday travelling south along the A9 highway. Later the convoy arrived in Omantai town in government-controlled territory.

UN spokesman in Colombo Gordon Weiss said a total of 40 UN staff had now pulled out. Some local employees had decided to stay.

"We are pulling out reluctantly" because of aerial bombing and artillery shelling, he told the BBC Tamil service.

A spokesman for the Roman Catholic aid agency, Caritas, said that it was "not possible to get the church out of the north" and its staff would remain.

Meanwhile, a bomb has wounded at least four people on a bus in the capital, Colombo, police say. There have been a number of such attacks blamed on the rebels in recent months.

Displaced

The BBC's Roland Buerk in Colombo says the military is pushing ahead with a major offensive to defeat the Tigers and end their fight for a separate state for the Tamil minority.

Troops are now near Kilinochchi

Fighting has intensified as soldiers continue a slow advance, aiming to crush the Tigers' de facto mini state in the north.

Key rebel bases have fallen, and the army says the Tigers have been driven from the east.

Military spokesman Brigadier Udaya Nanayakkara said troops were now just 5.5km (3.4 miles) away from the rebel headquarters at Kilinochchi.

Both sides claim to have inflicted heavy casualties on the other in fighting in Akkaraayan to the south-west of Kilinochchi district on Monday.

In Kilinochchi town itself, buildings around the hospital were hit by the air force and four civilians killed, a hospital doctor told the BBC Sinhala service.

Earlier, aid workers in the town told the BBC they could hear small-arms fire.

Last week, the government told aid workers employed by international organisations to leave the area, saying it could not guarantee their safety.

The International Committee of the Red Cross (ICRC) is being allowed to remain in the area. It operates a checkpoint between government and rebel-held territory.

The UN says the plight of civilians in the north is worsening

The government does not allow independent reporters into conflict areas, and many lines of communication to the north have been cut.

Aid agencies estimate there are 160,000 people in rebel areas who have been displaced by the fighting.

Leaflets have been dropped urging them to move out.

Sources on the ground say civilians are fleeing Kilinochchi into areas to the east, and rebel fighters are going that way too.

Asked if he planned to obliterate the Tigers, Sri Lanka's President Mahinda Rajapaksa told foreign correspondents the military would try, but it would take time.

"We are focusing on war," he said, Reuters reports. "We can crush them. Why can't we? They are in the jungle at the moment, and our forces are in the jungle at the moment."

Guerrilla warfare

The Liberation Tigers of Tamil Eelam (LTTE) have been fighting for a separate Tamil homeland in the north and east for 25 years. More than 70,000 people have died.

The rebels have come under sustained pressure from the government's air and ground forces, and they have been gradually forced to cede territory in several areas in recent months.

However, despite recent losses, the Tamil Tigers still hold considerable fighting ability to launch surprise counter attacks.

Contrary to some military claims, their core fighting formations are said to be still intact and they can easily adapt themselves to protracted guerrilla warfare, analysts say.

In July, Sri Lanka's army commander said the rebels had been defeated as a conventional force - but he conceded that a low-level insurgency could last forever.