GUWAHATI - Six troopers were killed Sunday and their weapons looted after rebels attacked their convoy in India's restive northeastern frontier state, police said.

The soldiers from Assam Rifles were returning from a landslide disaster site when rebels sprayed their vehicles with bullets in Chandel district, about 120 kilometres (75 miles) southwest of Manipur's state capital Imphal.

"The troopers were returning from a remote area close to the Myanmar border after inspecting an area hit by heavy mudslides when they came under attack from separatists armed with automatic weapons," a senior police official said, requesting not to be named as he was not authorised to speak to media.

The rebels were hiding on a hilltop and launched the attack before escaping with several AK-47 rifles and other weapons taken from the troopers.

One of those killed was from India's elite paramilitary force.

Herojit Meitei, Chandel police chief, told AFP that extra manpower had been deployed to find the attackers.

"We are trying to establish contact with our officers in the remote area. We are not yet clear about the damage," he added.

More than 19 militant groups are active in Manipur, with demands ranging from secession to greater autonomy.

Last June, rebels in Chandel district killed 20 Indian soldiers in a convoy attack.

The assault prompted India to launch a surgical strike in Myanmar which it claimed killed several militants.