NEW DELHI — Security forces killed at least 27 people in central India on Wednesday, in an operation that police said had targeted Maoist militants, as authorities intensify a military campaign aimed at defeating the country’s decades-old leftist insurgency.

Prabhat Kumar, a police chief in the state of Chhattisgarh, said that “several senior-level Maoist cadres” had been killed or seriously injured in the operation Wednesday. Local media reported that a top leader of the rebels, Nambala Keshav Rao, who goes by Basavaraju, was among those killed.

Last week, in another bloody confrontation, the government said it had killed 31 members of the movement in a hilly region between Chhattisgarh and a neighboring state.

Amit Shah, India’s home minister, called that operation a “historic breakthrough.” He has set a deadline of March for wiping out the whole of the insurgency, which has raged fitfully for more than 50 years.

Human rights activists have warned of the possibility that innocent civilians have been killed in the campaign against the rebels. Bela Bhatia, a lawyer who works in regions affected by the insurgency, said that while rapid identification of the bodies by family members was crucial, the government often took days to present corpses.

The Indian state regards the Maoists as an enormous threat, and critics say this has led to military excesses in clamping down on the movement. In 2009, the prime minister at the time, Manmohan Singh, called them the country’s “biggest internal security challenge.”