GUAHATI: A group of rebels ambushed a military convoy in India's insurgency-wracked northeast on Thursday, killing at least 20 soldiers and wounding 11 others in the latest major attack in the region in recent months, police said.

The ambush occurred as the convoy was on its way from a small town to Imphal, the capital of Manipur state, a police officer said on condition of anonymity because he was not authorised to talk to reporters.

Manipur, with a population of 2.5 million, has struggled for years in the grip of an armed insurgency in which several tribal militant groups are active.

The state, which borders Myanmar, has several active militant groups. None immediately claimed responsibility for the attack.

“We do not know as yet who is responsible,” said a spokesman at army headquarters in the capital, New Delhi.

In April, insurgents armed with automatic weapons fired at two trucks carrying Indian paramilitary soldiers in neighboring Nagaland state, killing eight of them.

The mountainous region, known for its natural beauty, has been battling insurgencies for decades.

Most of the main rebel groups in Manipur state are not engaged in cease-fire talks with the Indian government, unlike those in other remote northeastern states.

Separatist groups accuse the Indian government of exploiting the region's rich natural resources while neglecting local development.

Police said the ambush occurred Thursday as the convoy was on its way from a small town to Imphal, the capital of Manipur state.

The rebels have been called India's biggest internal security threat, operating in 20 of India's 28 states with thousands of fighters.

Also read: Eight troopers dead in rebel attack in north east India

Inspired by Chinese revolutionary leader Mao Zedong, they've been fighting for over three decades in central and eastern India to demand the poor receive more jobs and a greater share of wealth from natural resources.