COLOMBO, Sri Lanka - Sri Lankan forces captured the strategic Elephant Pass base from the Tamil Tigers on Friday, ousting the rebels from their last stronghold on the Jaffna peninsula and boxing them into a shrinking pocket of land in the northeast.

In a nationally televised address, President Mahinda Rajapaksa praised the victory.

"Our soldiers by this evening have been able to totally liberate Elephant Pass from the clutches of the" rebels, he said.

The capture of the base gives the government nearly full control of the northern peninsula, the Tamil's cultural capital, for the first time since 2000. It also puts the country's major north-south highway completely under its control for the first time in 23 years.

The rebels are now confined to a small area off jungle around their last remaining stronghold of Mullaittivu.

The rebels were not available for comment.

The government, which seized the rebels' administrative capital of Kilinochchi last week, has promised to crush the rebel group and end the Indian Ocean island nation's 25-year-old civil war.

But, in a reminder of the rebels' ability to cause destruction even as they suffer conventional defeats, the rebels detonated a roadside bomb in the country's east Friday that killed three air force troops and four civilians, military spokesman Brig. Udaya Nanayakkara said.

The attack outside the eastern city of Trincomalee signaled a return to guerrilla tactics. The government captured the east from the rebels in 2007, but attacks in the area have increased in recent months.

On Friday, government forces marching from the north and south broke into Elephant Pass and fought heavy battles with the rebels, the military said. The base is located on the isthmus connecting the northern Jaffna peninsula with the rest of the island.

Analysts said the guerrillas appeared to have withdrawn their artillery and heavy weaponry from the area and were sacrificing their bases on the peninsula to consolidate forces near Mullaittivu, where they will likely make a stand.

Human rights groups have warned that casualties among the hundreds of thousands of civilians living in the shrinking pocket of rebel territory were likely to mount as the government closed in on the insurgents.

The Tamil Tigers have been fighting since 1983 to create an independent homeland for ethnic minority Tamils, who have suffered decades of marginalization by governments controlled by the Sinhalese majority. The conflict has killed more than 70,000 people.

Troops south of Jaffna were also fighting the rebels, pushing eastward from the Kilinochchi area, Nanayakkara said. The troops found the bodies of seven insurgents from fighting Thursday, he said.