COLOMBO, Sri Lanka – Sri Lankan forces battled rebel gunmen deep inside the nation's northern jungles Thursday, killing 25 guerrilla fighters and seizing new territory, the military said. Other battles killed 25 rebels and four soldiers, the military said.

The fighting in the northern Mullaitivu district, a key part of the rebels' de facto state, began early Thursday morning and erupted into hours of gunbattles, said military spokesman Brig. Udaya Nanayakkara.

Troops eventually captured a section of rebel-held territory about two miles south of the village of Mallavi, which lies along a key road the rebels use for moving troops and supplies, he said.

Troops killed 25 rebels and recovered seven of their bodies, he said.

The fighting has escalated in recent months as top Sri Lankan officials vowed to crush the rebel group by the end of the year. Though military gains against the Tamil Tigers had been relatively modest, troops in recent weeks seized a string of key towns and rebel bases, consistently chipping away at the guerrillas' power base.

Keeping up the pressure on the group, air force jets hit a rebel training base and a gathering point for Tamil Tiger leaders in a pair of airstrikes in the north Thursday, the military said, without giving estimates of casualties or damage.

Navy boats also fought a sea battle with 10 boats from the rebel's naval wing, destroying three of them, the military said.

Government forces also killed 25 rebels Wednesday in battles in the Vavuniya, Mannar, Jaffna and Welioya regions along the front lines, the military said Thursday. Four soldiers were killed in those fights as well, it said.

Rebel spokesman Rasiah Ilanthirayan was not immediately available for comment. Both sides routinely exaggerate enemy death tolls while underreporting their own.

It was not possible to independently verify the military reports because the government has barred most journalists from the northern jungles where much of the fighting takes place.

The Tamil Tigers have been fighting for an independent state in the nation's north and east since 1983, following decades of marginalization by governments dominated by the Sinhalese majority. More than 70,000 people have been killed in the conflict.