Maoist rebels killed at least 16 people in a massive attack on security forces in central India Tuesday, less than a month before the country holds a general election.
Security officials and police sources said the victims were all killed when up to 200 rebels ambushed a patrol in forests in Chhattisgarh state, sparking a major gun battle that lasted for three hours.
Eleven members of the national paramilitary Central Reserve Police Force (CRPF) were killed along with four members of the state police force, said Mukesh Gupta, one of Chhattisgarh's most senior police officers.
"As of now, a total of 11 CRPF, four policemen and one civilian have died," Gupta told AFP.
Others suggested the death toll was even higher.
Rajinder Kumar Vij, the head of anti-Maoist operations in Chhattisgarh, put the number of CRPF personnel dead at 15 and said that five state policemen had also been killed.
There were no figures on the number of Maoist casualties.
- Indiscriminate firing -The forces were involved in an operation to clear and open a road in Sukma district when the rebels detonated a landmine and started firing indiscriminately, Vij told AFP.
"The attack sparked a gun battle that lasted about three hours."
Several people were injured in the attack and were airlifted to Ramkrishna Care Hospital in the state capital Raipur for treatment.
Security reinforcements were rushed to the area, along with top state government officials.
Gupta said the attack took place in a heavily-forested area during the operation to clear the road some 400 kilometres (250 miles) south of Raipur.
"The attack was on one of our police parties as the Naxalites (Maoists) have been frustrated at our increased presence in the area," he said.
"We don't yet know the casualties on the attackers side... It is difficult for us because of the topography of the area."
One of the top officers in the CRPF said that paramilitaries who had been deployed to the region in the attack's aftermath were wary of themselves becoming victims.
"The area is heavily mined and hence reinforcements are treading cautiously," Inspector General Zulfiquar Hasan told the Press Trust of India news agency.
The attack was close to the site of an ambush in May last year on a convoy carrying members of India's ruling Congress party in which 24 people were killed, including the state party president and his son.
- Election violence fears -The latest deaths will heighten fears of unrest in the Maoists' stronghold in the build-up to the nationwide elections which begin in early April.
Voting will take place in Chhattisgarh in three phases, on April 10, 17 and 24.
Ravi Shankar Prasad, a senior member of India's main opposition Bharatiya Janata Party (BJP), said authorities should not allow the attack to disrupt election preparations.
"The deaths are extremely unfortunate. We condemn it strongly. Whenever elections are held they resort to such tactics. They tried to derail last year's state elections as well but they did not succeed in their designs," he told a press conference in New Delhi.
"Naxalism is a national problem. Naxalites don't believe in democracy. I would like to ask some of the intellectual supporters of Maoists sitting in Delhi what do they have to say on this."
The Maoists, who have been described by Prime Minister Manmohan Singh as the country's most serious internal security threat, have been fighting since 1967 for a communist society by toppling what they call India's "semi-colonial, semi-feudal" form of rule.
The insurgency is believed to have cost tens of thousands of lives, with much action focused around the insurgent-dominated, so-called "Red Corridor" stretching through central and eastern India.
The Maoists are believed to be present in at least 20 states but are most active in Chhattisgarh, Orissa, Bihar, Jharkhand and Maharashtra, occupying thousands of square kilometers (miles) of land.
Critics believe attempts to end the revolt through security offensives are doomed to fail, saying the real solution is better governance and development.
Tuesday's attack is the deadliest so far this year although six policemen were killed on February 28 in Chhattisgarh.