At least 18 naxalites have been killed in a fierce encounter with Central Reserve Police Force (CRPF) personnel in the jungles of Dantewada district of Chhattisgarh on Friday.

The six hour overnight encounter also injured nine CRPF officials and two CoBRA commandos, all of whom were shifted to a Rajpur hospital for treatment of bullet injuries.

According to Indian news agency Press Trust of India, the combat broke out in the dense jungles of Silger village, which is a "liberated" Maoist zone between the naxal hub of Jagargunda and Basaguda in Dantewada district.

The encounter began Thursday night, when CRPF personnel plunged into warfare with the naxalites upon learning of their presence in the jungle.

Amongst the others injured were two Maoists who were called in for questioning and were arrested.

Central forces considered the operation a success as it is the first time central forces have shot down a high number of Maoist casualties.

Reports suggest that the death toll of the Naxalites may surge given that the casualty information is seeping out at a slow pace.

Local villagers, mostly those from the tribes, challenged the police claim and protested that those killed in the encounters were villagers rather than insurgents, BBC news reported.

Prashant Agarwal, a senior police officer in Bijapur, told BBC that authorities have seized a large number of arms and ammunitions, including a bomb, from that area.

Out of the 18 bodies discovered only five of them have been identified so far, Agrawal added.

According to reports, firing in the area is still prevailing and additional troops and logistics have been dispatched in order to bring the situation under control.        

The area, were the attack was launched, is close to Chintalnar in Chhattisgarh. In April 2010, the biggest ever attack on security forces were carried out at the same place which killed 75 CRPF men and one state police personnel.