The detention in barbed wire camps in Sri Lanka's north of some 280,000 Tamil civilians since they fled Tamil Tigers territory before the military crushed the rebels has caused widespread concern.

On Friday, Maran had separately called on the prime minister as an emissary of Karunanidhi to 'highlight the plight of the displaced Tamils' in the Sri Lankan camps.

Karunanidhi wanted Manmohan Singh to 'exert diplomatic pressure at appropriate levels' on Colombo to end what he said was 'untold suffering' of the displaced Tamils.

Baalu alleged that the Sri Lankan government was not allowing the Tamil refugees to return to their native places, which were under the control of the LTTE before it was defeated.

'We told the prime minister that Tamils are stranded in the refugee camps. Around 2,000 Tamil civilians who were allowed to move to their native places have not reached there,' Baalu said. 'We want to know what happened to them.'

The delegation also urged the prime minister to take immediate steps to stop attacks by the Sri Lanka Navy against Indian fishermen in the sea, Baalu said.