A rare video footage of Maoists purportedly showing the rebels conducting a 'commando-style' training to gun down helicopters, used to ferry security personnel and VIPs in Chhattisgarh's worst insurgency-hit Bastar region, has been recovered by police.

The video of the outlawed CPI (Maoist) at a training camp apparently in forests of Sukma - south Bastar adjoining Andhra Pradesh and Odisha - shows a group of 15-20 guerrilla cadres doing a practice to bring down a chopper by using its 'dummy' with LMGs (light machine guns) and small weapons.

"Documents detailing Naxals' nefarious strategies to target choppers have been seized a number of the times from various places of Bastar, but for the first time it has come to our knowledge that they have made its clippings. Now it's clear that the Naxals are conducting such trainings," state Additional Director General of Police (anti-Naxal operations) R K Vij told PTI.

"Security will be beefed up around helipads in the dense forests and all necessary precautionary measures will be taken to ensure that Maoists do not get a chance to target choppers," Vij said.

The video clip, believed to be shot recently, shows a dummy of a flying machine, prepared with raw wood, plastic sheets and branches of trees, suspended on a rope tied to trees from two sides.

In the footage, few cadres are seen swinging off the 'dummy' from one side to another in a descending pattern, quite like a helicopter lands from some specific height at the helipad, while the armed cadres positioned on the ground are seen firing at its bottom.

The video also shows Maoists training in different techniques to engage helicopters with small weapons along with some sophisticated weapons positioned at strategic points.

Machine guns mounted on tripods made of tree branches were also being used in the training, as per the footage.

A Central Reserve Police Force (CRPF) official posted in Chhattisgarh said, "We have received number of inputs that they are being trained to bring down choppers generally used in casualty evacuation mission and to ferry VIPs and VVIPs."

Maoists generally try to fire at copters at the time of landing and take-off from around a kilometre away from the landing site, but they hardly get any success, he said on condition of anonymity.

The rebels have also tried to divert the choppers to land at a wrong place in the dense forests, but they have never been successful in it, the paramilitary official said.

As per police statistics, the Naxals last year looted as many as 41 assault rifles, including AK-47, Insas and SLR, after encounter with security forces in Bastar.

Around eight of the snatched sophisticated weapons were built with Under Barrel Grenade Launchers (UBGL), which has a capacity to target to at least 800 metres.

"The looted sophisticated weapons could be used to target choppers. We have asked our men to trace the locations of such camps (if any) meant to train to shoot down choppers, in Sukma and Bijapur," the CRPF official said.

In the past, the Naxals had targeted choppers several times in Bastar.

In January 2013, an IAF helicopter, on a rescue mission to airlift an injured CRPF jawan and the body of another, was forced to make an emergency landing at a field in the densely-forested Sukma district after it came under fire from Maoists.

In another incident in Sukma, Naxals had fired at an IAF helicopter flying to retrieve an injured CRPF personnel in November last year. An IAF commando had sustained bullet injuries on his leg in the Naxal firing.