New Delhi  - At least four police officers and four Maoist militants were killed in India's central state of Chhattisgarh, which was placed on alert Monday amid intelligence reports that the rebels could strike urban areas, officials and news reports said.

The police officers from the Central Industrial Security Force were killed Sunday evening when Maoists triggered a landmine blast to blow up their jeep, senior police official RK Vij told reporters.

The explosion took place in a village in the Dantewada district, a stronghold of the rebels, located about 400 kilometres south of the state capital, Raipur.

The police were part of the security force at iron-ore mining facilities at the state-run National Mineral Development Corp.

Security forces also gunned down four Maoist insurgents, including a woman, in three separate shootouts Sunday in thickly forested areas of the state's Bijapur and Narayanpur districts, the IANS news agency reported.

Meanwhile, security in and around key installations in Raipur was intensified after intelligence reports that Maoists with access to rocket launchers were keen to strike urban areas to halt security operations against them.

With more than 40,000 police and paramilitary troopers planning to raid guerrilla hideouts in the remote, Maoist-dominated areas of the state, the banned Communist Party of India-Maoist was desperate to take the battle to towns and cities, particularly Raipur, officials told the IANS.

"We have gathered enough intelligence inputs in recent days that say Maoists are keen to strike in urban areas of the state, including Raipur at its key government installations, to somehow halt the ongoing operation against them in their strongholds," a senior official told IANS, requesting anonymity.

Maoist rebels, who said they are leading an armed rebellion to secure the rights of the poor and marginalized, operate in 20 of India's 28 states. They usually target security personnel and government installations and officials.

At least 2,671 people - including civilians, security personnel and rebels - have been killed in incidents related to Maoist violence in India since 2006, according to Home Ministry data. (dpa)