Five Central Reserve Police Force jawans were killed and eight injured in an ambush at Keithelmanbi in Manipur's Senapati district on Wednesday, official sources said.

The militants, who were hiding by the roadside, fired at the CRPF convoy of 143th battalion when the latter reached the hilly Keithelmanbi area.

The militants also threw grenades at the vehicles of the security personnel before firing, sources said.

It was yet to be ascertained which insurgent outfit was behind the ambush.

The CRPF personnel, who were returning to their camp at Lamphel area from Kotlen, retaliated and the exchange of fire lasted more than two hours, sources said.

In the gunbattle, at least 13 CRPF personnel sustained injuries. Of them, five died on the way to and in hospital.

The bodies were kept at the Regional Institute of Medical Science and Hospital for post-mortem.

The condition of the injured, being treated in the same hospital, was stated to be serious.

Casualty, if any, on the side of the militants was not immediately known, sources said.

On Sunday, militants of the banned People's Revolutionary Party of Kangleipak had attacked a group of Assam Rifles personnel killing one jawan and injuring another at Umathel area in interior Thoubal district.

Official reports said angry Assam Rifles personnel had beaten up about 45 villagers, including women of Umathel after the ambush.