The Tamil Tigers last week accused the government of planning a genocidal campaign against Tamils as UN agencies began pulling out of the LTTE-held Vanni regions in the island's north
The United Nations pulled its staff out of the LTTE-held northern region after being ensured safe passage by government troops and the Tamil Tigers.
Other aid agencies have also left, after being initially prevented from doing so by displaced people.
Residents had gathered outside the offices of the UN Refugee Agency (UNHCR) and the World Food Programme on 12 September in an effort to prevent the pullout, demanding that the agencies stay behind and continue their humanitarian work for the Vanni people facing a humanitarian crisis.
The agencies' move comes as the army continues a major offensive against the LTTE in northern areas of the island.
The government ordered aid workers out of the north earlier this month saying they could not guarantee their safety.
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 16 September 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.
UN agencies say at least 160,000 people have been displaced in the past few months in the districts of Mullaittivu and Kilinochchi. Some 70,000 people have fled due to fighting in the past two months alone.
Leaflets have been dropped urging them to move out, but Médecins Sans Frontières (MSF) noted that there is little evidence that civilians have been able to move to safety.
According to the Consortium of Humanitarian Agencies, 11 UN and other agencies have been working in the Vanni area.
Meanwhile, MSF expressed concern about the possible consequences of ongoing hostilities for the population still living in the area, and the impact of displacement on the health of the population.
The organisation urged both parties to the conflict to ensure that all possible measures are taken to protect civilians from the impact of the conflict, and to allow assistance to resume as soon as possible.
Apart from potential exposure to shelling and bombardment, those who have been forced to leave their homes lack adequate shelter, sanitation facilities and access to clean drinking water, the organisation noted.
“The potentially serious health impact will only be worsened by the arrival of the rainy season begins in roughly a month's time. Existing hospitals and clinics have also been affected by the fighting, and though the system is compensating for the moment, if the situation is prolonged there will be serious shortages of medicines and supplies, as well as qualified medical staff,” MSF noted.
“MSF is prepared to return to Kilinochchi as soon as possible,” the organisation said, adding that in the mean time, “the withdrawal should not affect programmes in other parts of
The International Committee of the Red Cross (ICRC) is being allowed to remain in the area. It operates a checkpoint between government and LTTE-held territory.
The government does not allow independent reporters into conflict areas, and many lines of communication to the north have been cut.
