COLOMBO, Sri Lanka (AP) - Sri Lankan troops fought off an attack early Friday from ethnic Tamil rebels trying to recapture lost territory, as violence in the northern battle zone killed 46 rebels and three soldiers, the military said.

The Tamil Tigers' pre-dawn attack came hours after government forces captured a section of rebel-held territory near a key supply route in the Mullaitivu district, about two miles south of the village of Mallavi, said military spokesman Brig. Udaya Nanayakkara.

"They came to attack, and we surrounded them and attacked (back)," he said in describing the second battle over the territory.

Troops killed 33 rebels in the fighting, recovering all of their bodies, and were searching the area for more rebel fighters, he said.

Meanwhile, battles in other parts of the war zone Thursday killed 13 rebels and three soldiers, he 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.

Meanwhile, the Tamil Tigers accused an undercover military unit of setting off a roadside bomb inside rebel-held territory that killed a development official as he rode past on a motorbike, according to a Web site run by the rebels' peace secretariat.

The rebels have routinely accused the government of sending so-called deep penetration units into their stronghold to carry out guerrilla attacks.

Nanayakkara denied the military was behind the attack, saying that Sri Lanka's troops were busy with the fighting near Mallavi.

"We were completely concentrating on that area," he said.

Fighting has escalated in recent months as top Sri Lankan officials vowed to crush the rebel group and seize its de facto state in the north 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.

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.