Sri Lanka accused of killing civilians and aid workers

Fighting in Sri Lanka has dramatically worsened, as the UN humanitarian chief called for an independent investigation into the killing of 17 international aid workers. The Tamil Tiger rebels claimed 50 civilians were killed in the areas they control after the government launched a renewed offensive with ground forces backed with air strikes and artillery fire.

There was no way of confirming the Tigers' claim, but European ceasefire monitors said the rebels had informed them of 30 to 40 civilian deaths and they considered the figures credible. If they are true, they represent the worst civilian casualties in a single day since the fighting started. As many as 300 civilians are feared to have been killed in all, and tens of thousands have fled their homes.

The Sri Lankan military said it had no information about civilian casulaties, but sought to blame any on the Tigers. The guerrillas are "known for using civilians as human shields and they place their gun positions around civilian villages", said Major Upali Rajapkse, a military spokesman. "The Sri Lankan army does not target civilians."

The new offensive comes despite the reopening of the water supply the government said was the sole reason for the fighting. Colombo launched the first ground offensive since a 2002 ceasefire after the Tigers blocked a water canal. But the water supply was reopened by Wednesday.

The government says it is continuing operations to clear the area of Tigers, to the dismay of Western diplomats. "The situation is worsening," said Robert Nilsson, a member of the European monitoring team. "Hopefully there will be a change of heart, this has already gone too far." The call by Jan Egeland, the UN's most senior humanitarian official, for an independent inquiry into the aid workers' killings is a sign that the controversy over their killings is not over for the government. Relatives of several of the victims have openly accused government forces of being responsible for their deaths.

Seventeen employees of the French non-government organisation, Action Contre la Faim, were found dead after fighting in the town of Muttur, where they were engaged in tsunami relief.

Fifteen were found lying face down in their office with bullet wounds to the head. Two who were found in their car nearby, appeared to have been fleeing when they were killed.

All were wearing T-shirts which clearly identified them as humanitarian workers. "We're now demanding an independent investigation in Sri Lanka into how this could happen, execution-style, to humanitarian, unarmed workers," said Mr Egeland.

The Sri Lankan government has already promised a full investigation. The government and the Tigers have both accused each other of repsonisbility, and no one has yet produced definitive evidence as to who was responsible. But the relatives' accusations have hurt the government, even as its international credibility is being damaged by the fighting.

Before the government's ground offensive, Western diplomats unanimously put the blame for the deteriorating situation in Sri Lanka on the Tigers, after a series of attacks on the Sri Lankan military, including the assassination of a senior general. Those attacks were seen as a blatant attempt to push the government back into a war, and the government was widely praised for its restraint.

But diplomats are much more reluctant to support the government after it continued its offensive despite the reopening of the water supply. The water issue looks increasingly like an excuse, with the government offensive concentrated in an area where the Tigers are known to have major military resources.