GUWAHATI, India (Reuters) -- India has ended a truce with rebels in the country's northeast and resumed a counter-insurgency operation after militants killed two people, including a policeman, an army official said on Sunday.

Military operations against the separatist United Liberation Front of Asom (ULFA) were suspended on August 13 by New Delhi, after the rebels offered to engage in peace talks to end the nearly three-decade-old conflict in the state of Assam.

"Army operations have resumed and soldiers have moved out of their barracks in upper (eastern) Assam," a senior military commander told Reuters by phone from Dibrugarh, about 400 km (250 miles) from Assam's capital, Dispur.

The truce was initially for a few days but was subsequently extended after talks between government officials and representatives of ULFA. But both sides had said it was not a formal ceasefire.

The federal government called off the truce after suspected militants shot dead a policeman and a tea estate manager in two separate incidents on Friday and Saturday where they were trying to extort money.

The remote northeast, linked to the rest of the country by a strip of land just 32 km (20 miles) wide, is home to seven of India's 29 states and is surrounded by China, Myanmar, Bangladesh and Bhutan.

The region has more than 200 ethnic and tribal communities and two dozen rebel groups. Several people die each week in rebel violence.

The ULFA, which has been fighting a war of secession in oil, tea and timber-rich Assam since 1979, is thought to be demanding the release of jailed senior rebels before peace talks can begin in earnest.

It accuses New Delhi of neglecting the state and taking away its natural resources. About 15,000 people have been killed in the insurgency so far.