The east coast has seen several confrontations

The incident occurred as navy vessels headed towards two boats off the coast of Vakarai in eastern Batticaloa district.

It is yet to be confirmed whether the boats belonged to Tamil Tigers.

But the incident follows several confrontations off the east coast since a permanent truce was signed in February between the government and the rebels.

The AFP news agency quoted defence ministry spokesman Mr Karunaratne as saying there was no firing from either the navy vessels or the boats.

Truce monitors

Mr Kunaratne said the second vessel headed towards the coast, where the army has been alerted.

Previous confrontations between the navy and the Tigers have been resolved by the intervention of Scandinavian truce monitors.

The Tigers have not commented on the latest incident.

Late last month, the navy said it intercepted three boats carrying some 40 Tamil Tiger rebels.

The navy said Scandinavian peace monitors were called in and the rebels were then allowed to disembark, with no fighting taking place.

Despite complaints from both sides of ceasefire violations, the truce is still holding.

The two sides are due to hold peace talks in Thailand in June, aimed at ending to almost two decades of civil war.

More than 60,000 people have died in the fighting.