Maoist rebels ambushed paramilitary forces in eastern India's Chhattisgarh state on Monday (24 April), killing at least 25 policemen. Six others were injured in the attack that Prime Minister Narendra Modi condemned as "cowardly and deplorable".

The attack on the team of Central Reserve Police Force (CRPF) took place in Sukma district, which is one of the worst-Maoist affected districts in the country. It is located about 450km from the state capital Raipur.

The deadly massacre was reportedly carried out by about 300 Maoist insurgents who were armed with rifles. The 99 CRPF policemen were deployed to provide security for road construction in the area when the leftist rebels ambushed them.

"Security forces will move with ease in the area after this road is built and this is troubling the Maoists. We are entering their core through this road," local media cited D M Awasthi, special director general of police (anti-Maoist operations) as saying.

The insurgents reportedly looted radio sets from the slain police personnel in the region, leaving the survivors without any device to call for help.

One of the survivors told the Hindustan Times newspaper that the forces retaliated and shot and killed several rebels.

"The troops replied in a befitting manner but taking advantage of their geographical position, the Maoists succeeded in inflicting losses on the CRPF," the paramilitary force said in a statement.

Condemning the attack, Modi tweeted: "Attack on @crpfindia personnel in Chhattisgarh is cowardly & deplorable. We are monitoring the situation closely."

He added that the sacrifice of the martyrs would "not go in vain".

Home minister Rajnath Singh tweeted that he was "extremely pained" to know about the assault. He is visiting Chhattisgarh to take stock of the situation on Tuesday (25 April).

"It is a very sad and unfortunate incident... We have taken the attack as a challenge," Singh said.

The assault is believed to be one of the deadliest attacks on CRPF personnel in recent times. Earlier in March, at least 11 policemen were killed in the same region.

Nearly 200 of them are reported to have died in six major attacks in Chhattisgarh since April 2010, local media reported.

Maoist rebels have been involved in an armed insurgency against the state for several decades. They control several areas in the north-eastern and central Indian states. They have long argued that they are fighting for the rights of the local community and landless farmers. They say they want to oust local governments to establish an egalitarian society for the tribal people.