As many as 22 Indian police and paramilitary forces personnel were killed and 30 others wounded in a gun battle with Maoist rebels in a central Indian state, police said on Sunday, in the deadliest ambush of its kind in four years.

Some 2,000 security personnel were on the hunt for a Maoist rebel leader in Bijapur district in Chhattisgarh state on Saturday when they were ambushed, a police officer told AFP.

“So far it is confirmed that 22 security personnel were killed,” Chhattisgarh police's Additional Director General Ashok Juneja said of the almost three-hour battle in the Maoist rebel stronghold.

“The search operation is still underway and the exact figure will be known ... late Sunday evening.” The injured personnel were admitted to two government-run hospitals in Bijapur and Chhattisgarh's capital city Raipur.

More than a dozen others remained missing, he said, adding that an unknown number of Maoists were also killed in the encounter.

Juneja said the rebels looted weapons, ammunition, uniforms and shoes from the security forces who were killed.

The death toll could rise further, another senior police officer in Bijapur district told AFP.

Prime Minister Narendra Modi tweeted that the “sacrifices of the brave martyrs will never be forgotten”, while Home Minister Amit Shah wrote on Twitter that India would “continue our fight against these enemies of peace & progress”.

Chhattisgarh Chief Minister Bhupesh Baghel wrote on Facebook on Sunday that Shah had assured him of “all the necessary help” from the national government against the militants.

The toll was the worst for Indian security forces battling the far-left guerillas since 2017, when 25 police commandos were killed in an attack.

Seventeen police from a commando patrol were killed in an attack by more than 300 armed rebels in Chhattisgarh in March last year.

Sixteen commandos were also killed in the western state of Maharashtra in the lead-up to India's election in 2019, in a bomb attack that was blamed on the Maoists.

The Maoists, also known as Naxals, have waged an armed insurgency against the government for decades.

Leaders of the hardline leftist militant group say they are fighting on behalf of the poorest, who have not benefited from a long economic boom in Asia's third-largest economy.

Thousands have been killed in the fighting.