Colombo (AP): Sri Lankan forces battled rebel gunmen deep inside the nation's northern jungles on Thursday, killing 25 guerrilla fighters and seizing new territory, the military said. Other battles killed 25 rebels and four soldier, the military said.

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

Troops eventually captured a section of rebel-held territory about three kilometers 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 Lakan 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 base, 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 Tigers leaders in a pair of airstrikes in the north today, the military said without giving estimates of casualties or damage.