Sri Lanka's military on Monday destroyed 10 Tamil Tiger boats, the military said.

In another tangible sign of progress made by a military campaign that has taken nearly 15,000 square km (5,790 sq miles) back from the rebels in two-and-a-half years, the military opened the main northern highway for the first time in 24 years.

Liberation Tigers of Tamil Eelam (LTTE) rebels in boats attacked troops advancing toward a no-fire zone in the Indian Ocean island nation's northeastern coast, the military said.

"Ground troops attacked and destroyed 10 LTTE boats which came to attack them from Chalai," military spokesman Brigadier Udaya Nanayakkara said.

Chalai is immediately to the north of the no-fire zone, where tens of thousands of civilians are trapped by the Tigers in what aid agencies and diplomats say are rapidly deteriorating conditions.

The no-fire zone is inside the less than 50 square km to which the Tigers are now confined. Much of the fighting there is concentrated in Puthukudiyiruppu, the last town of which the Tigers control any part and where fighting has been heavy.

The military says the LTTE has been firing from inside the no-fire zone, and the rebels have repeatedly accused the government of firing into the area. The military denies that and last week said soldiers were taking more casualties as a result.

The Tigers, on a host of international terrorism lists, say they have been fighting to create a separate state for Sri Lanka's Tamil minority.

One major symbol of that had been a checkpoint along the A-9 highway linking southern Sri Lanka to the northern territory they controlled, where the LTTE had collected taxes from passing vehicles.

On Monday, the military ceremonially reopened the A-9 for military transportation, for the first time since the rebels seized part of it in 1984. Already, the military has repaired parts of the road in anticipation of resuming normal traffic.

The A-9 links southern Sri Lanka to the northern Jaffna Peninsula, an ethnically Tamil area where the rebellion got its start.

The army re-captured Jaffna in 1995 but the long closure of the A-9 has made sending food and other necessities to Jaffna hugely expensive because it requires air or sea shipments.

Reuters