By Sandeep Sahu BBC reporter in Bhubaneshwar

At least 18 policemen have been killed and several others seriously injured in a night-long ambush on the Orissa-Jharkhand border in eastern India.

The attack was carried out on Friday by the Maoist Coordination Centre (MCC) - an extremely violent outfit of rebels fighting for land reforms and the rights of the tenants.

All of the dead men were members of Jharkhand state police.

Fifteen of the injured policemen have been taken to hospital in Rourkela, on the Orissa side of the border.

There are no reports as yet of any casualties on the Naxalite side, according to sources in the Orissa police.

Night time

The guerrillas also seized more than 50 rifles belonging to the policemen and set three police vehicles alight.

The encounter, which began last night, was still continuing when reports last came in.

Deputy Inspector General (DIG) Sunil Ray, a senior official of the Orissa state police, has confirmed the 18 deaths but said there have also been casualties on the other side.

He was, however, unable to say how many Naxal guerillas had been killed.

DIG Ray said several policemen from the group, which was on its way back from a combing operation, were still trapped inside the forests.

Reinforcements from both Jharkhand and Orissa have been rushed to the area to rescue their trapped colleagues.

More casualties

The armed police of Jharkhand have now been joined by their counterparts from the neighbouring state of Orissa.

Sources in the Orissa police did not rule out the possibility of more casualties on the police side.

The Jharkhand-Orissa border areas have witnessed increased Naxal violence in the last few days.

Last week, a lower level forest department official was beheaded, supposedly for his anti-poor and anti-tribal actions.

Around 24 hours later, the head of a local village was taken from his home and killed in full public view.

The areas where these killings took place are close to Tirilposhi, where the encounter between the rebels and policemen is taking place.