"None of the international human rights organizations have even raised a voice or given a statement over these incidents," defence spokesman minister Keheliya Rambukwella told a news conference.

Rambukwella charged rights groups of being biased in dealing with human rights violations in the island and said that they are working on an "agenda" aimed at tarnishing Sri Lanka's image.

"They are acting in total bias on a different agenda . . . may be on various considerations . . . to bring the country into disrepute."

He was referring to strong criticism of alleged human right violations by the security forces in their campaign against the Tamil Tigers.

"On the other hand they have been trying to accuse the government for things that have not been proved or things that are being investigated," he said.

The government has said it is investigating allegations of human rights abuses by its forces.

It has also complained that Western countries and human right groups do not pay enough attention to human rights abuses by the Tamil Tigers, such as deliberate attacks on civilians.

A string of attacks that bore the hall marks of the Tamil Tigers killed and wounded scores of civilians in recent weeks.

The attacks include raids on remote Sinhalese villages as well as bombings of buses and railway stations packed with commuters.

Rambukwella said the Tigers, through such attacks on civilians including the deaths of school children, were trying to provoke a backlash by the majority Sinhalese community against minority Tamils so they could "market" it to the international community.

"If that happened the international community is waiting to buy that."

The Sri Lankan military has said the Tigers were resorting to attacks on civilians to divert the army's attention after suffering a series of setbacks in the north and east.

Human rights groups and Western countries which are Sri Lanka's main aid donors have been pressing the government to improve its human rights record.

Some countries have already curtailed aid and threatened to cut off aid altogether.

But the Sri Lankan government has rejected the allegations, saying the security forces take care to minimize civilian casualties in operations against the Tigers.

Government officials have also said that harm caused to civilians in Sri Lanka's war is much less than that inflicted by American and European security forces in other conflict zones like Iraq and Afghanistan.