COLOMBO, Sri Lanka - Battles between government forces and separatists Tamil Tiger rebels across Sri Lanka's war-ravaged northern region killed 31 rebels and 11 soldiers, the military said Monday.

Military spokesman Brig. Udaya Nanayakkara said army troops fought insurgents Sunday on three fronts separating the government-held territory and the rebels' de facto state in the north.

He said soldiers pushed into rebel-held territory in the Welioya area and captured five positions close to a major guerrilla base deep in the jungles after a battle that killed 20 rebels and eight soldiers.

The same battle wounded 41 rebels and 30 soldiers, he said, adding that one of the soldiers was missing.

Separate clashes in the Vavuniya district killed 10 rebels and wounded three soldiers, while in the Jaffna peninsula another confrontation killed three soldiers and one rebel, Nanayakkara said.

Rebel spokesman Rasiah Ilanthirayan could not immediately be reached for comment. The pro-rebel TamilNet website said rebels "thwarted three repeated attempts by the Sri Lanka Army" to break into the rebel-controlled territory in Vavuniya throughout Sunday.

The site did not give details of casualties.

It was not possible to obtain independent confirmation of the reported fighting. Both sides often release contradictory versions of attacks that take place in the embattled north, where access is restricted.

Fighting has escalated in recent months. The government has pledged to capture the rebel territory and crush the insurgents by the end of the year. Diplomats and other observers say the army has faced more resistance than expected.

The Tamil Tiger rebels have fought since 1983 to create an independent state for the island's ethnic minority Tamils who have suffered marginalization by successive governments controlled by majority ethnic Sinhalese. More than 70,000 people have been killed in the conflict.