Witnesses saw jets roar from their base north of the capital, Colombo, to attack the suspected base near the village of Verugal where rebels control a dwindling pocket of land in the far northeastern districts of Trincomalee and Batticaloa.

The Tigers were not available for comment and there were no immediate details of any damage or casualties.

"To neutralise the attacks against the army, the air force this morning ... took selected targets west of Verugal," said air force spokesman Group Captain Ajantha de Silva.

The military also paraded five Tamil youths in front of the media, saying they were Tigers who had surrendered, but there was no independent confirmation of their identities.

The army said it captured a stretch of the Tigers' defences along a battlefront in the east on Tuesday and killed around 30 rebels, but the Tigers denied it and said 12 of their own fighters died and that they killed 45 army troops.

The military said four soldiers were killed during Tuesday's fighting, which came as the government sought to evict the Tigers from territory they control in the east under the terms of a tattered 2002 truce.

Verugal is at the northern end of a 20-km long pocket of rebel-held territory around 240 km northeast of Colombo.

An estimated 10,000-15,000 Tamil civilians have been trapped by fighting in the town of Vakarai at the southern end, but 20,000 others have fled to government areas in recent weeks.

Foreign aid groups are clamouring for access to the area, which the government has denied.

In a report published on Tuesday, UN Secretary-General Ban Ki-moon called for an immediate halt to the fighting, and urged both the Tigers and a group of breakaway fighters the military are suspected of helping to stop recruiting children as soldiers.

"I stress the need for the government to investigate immediately allegations that certain elements of the Sri Lanka security forces are involved in aiding the recruitment and or abduction of children by the Karuna faction in the east," Ban said in the report published on Web site www.un.org.

"I call on the government of Sri Lanka and all relevant parties to ensure open and safe access by humanitarian actors in Sri Lanka to affected areas," he added.

The Tigers resumed their fight for an independent state for minority Tamils in the north and east after the government rejected their demands for a separate homeland. Analysts fear this new chapter in a war that has killed more than 67,000 people since 1983 could escalate.