The soldiers belonging to the Central Reserve Police force were ambushed in West Midnapore district, nearly 175 km west of Kolkata, the capital of West Bengal state, said Zulfikar Hassan, an inspector-general of police.

The attack came a day after India's home minister offered to begin peace talks with Maoist rebels, but only if they halt all attacks for 72 hours.

The offer followed a rebel ambush Monday of a bus in central India that killed 31 police officers and civilians.

The attacks highlighted the Maoists' strength despite a government offensive aimed at ending one of Asia's longest rebellions.

Suspected Maoist rebels moved into parts of West Midnapore district of West Bengal state last year after driving out poorly armed local police and seized control of villages in a 20-square-mile area. Security forces later drove them out from most of the area.

Inspired by Chinese revolutionary leader Mao Zedong, the rebels have fought for more than four decades demanding land and jobs for farmers and the poor. About 2,000 people — including police, militants and civilians — have been killed in the past few years.

The rebels, who have tapped into the rural poor's growing anger at being left out of the country's economic gains, are now present in 20 of the country's 28 states and have an estimated 10,000 to 20,000 fighters, according to India's home ministry.

Prime Minister Manmohan Singh has called them India's biggest internal security threat.

Last year, the government announced its “Operation Green Hunt” offensive aimed at flushing the militants out of their forest hideouts.