In one horrific video, a Boko Haram suspect is pulled from a truck and held down while a man in military uniform slices his neck open with a combat knife, hurling his body into a pit.The scene is repeated with another suspect on the same bloodied patch at the edge of the grave.Detainees are kept to one side while graves are dug before the pit is shown half-full of bloodied bodies. The video also shows images of men being pulled off the back of trucks and beaten by soldiers and allied civilian militias.The video, which was obtained by Amnesty International, has yet to be independently verified but the organisation insist it came from 'numerous sources' in Borno state, the militant group's birthplace and stronghold.The footage reveals 'graphic evidence of multiple war crimes being carried out in Nigeria,' according to Amnesty, which says it has independent confirmation from several military sources that the armed captors 'were indeed military personnel.'Nigeria's military is battling an increasingly vicious Islamist insurgency by Boko Haram, which wants to carve an Islamic state out of religiously mixed Nigeria. But its forces have come under fire for human rights abuses, including torture and killings they usually deny.Amnesty said the killings occurred shortly after Boko Haram's attack on a detention centre in Giwa Barracks, in the northeastern city of Maiduguri, on March 14.Nigerian Defence spokesman Major-General Chris Olukolade, said: ‘The military authorities view these grave allegations very seriously.‘Much as the scenes depicted in this video are alien to our operations and doctrines, it has to be investigated to ensure that such practices have not crept, surreptitiously, into the system.’He added that such behaviour would be counter to the training Nigerian troops are given.‘That level of barbarism and impunity has no place in the Nigerian military. Respect for the sanctity of life is always boldly emphasized in our doctrinal training,’ he said.The footage comes a week after Boko Haram leader Abubakar Shekau released a video of his fighters beheading a Nigerian soldier.(dailymail.co.uk)Bakudaily.Az