New Delhi  - Security forces in India's north-eastern state of Manipur have launched a large-scale manhunt for a paramilitary trooper who shot dead six of his colleagues, news reports said Thursday.

The unnamed trooper had an argument with an officer late Wednesday after which he picked up an assault rifle and fired at him, the IANS news agency quoted a defence spokesman, Major Shamser Jung, as saying.

When other colleagues rushed to the spot the trooper fired at them as well. The officer and five other troopers were killed on the spot, Jung said. At least two troopers were critically injured.

"Efforts are on to nab him, but the trooper is still at large after he fled the camp with his service weapon late Wednesday," Jung said.

"We don't really know what led to this or what the reasons were for the verbal argument," he added.

The trooper hailed from the neighbouring Nagaland state, the official said.

The incident took place at the barracks of the 17 Assam Rifles at Ukhrul, about 90 kilometres north-west of Manipur capital Imphal.

The 17 Assam Rifles is currently engaged in counter insurgency operations in Manipur, which borders Myanmar. At least 19 armed rebel groups are believed to be operating in the state. Their demands range from independence to greater autonomy. (dpa)