A video which shows children as young as three being encouraged to hold guns has been seized by counter-terrorism police in a raid in Manchester.

Officers say it is evidence of attempts by Islamic extremists to radicalise youngsters.

It shows two children, aged about three and six, playing with a pistol and a Kalashnikov rifle.

The footage, which it is believed to have been filmed in Pakistan, was found on the hard drive of a computer during a raid carried out under the Terrorism Act 2000.

A boy and a girl are seen playing with the guns, and a man's voice says: “What do you do with the weapon?”

He answers his own question with: “I want to kill the infidels [non-believers].”

A senior officer in the Counter Terrorism Unit (CTU) said: “We believe this was filmed abroad. We have no idea who the children are. We were shocked to find it at the house. We have no reason to believe this is faked. The guns are real.”

Police refused to say when the raid took place, and exactly where in Manchester.

In another house raid, a series of flash cards to teach children the alphabet were found.

The officer said: “The cards were written in English – and instead of having M for Muhammad they had M for Mujahideen.

“They have the potential to indoctrinate. It just shows the mindset of some people and what we are up against.”

Police also found documents downloaded from an extremist website which instructs parents to teach children about jihad, or holy war, from an early age.

The documents says: “The key is to start instilling these values in them while they are babies. Don't wait until they are seven. No child is ever too young to be started off on Jihad training.”

David Thompson, Assistant Chief Constable of Greater Manchester Police, said: “My view is that the majority of the community across the board see the threat that we're dealing with and are hugely supportive.”

Kim Howells, MP, chairman of the parliamentary intelligence and security committee, who was shown the footage, said: “It's a dreadful thing to see and I hope I never have to see it again actually.

“That's a serious piece of evidence of the kind of thing we are up against as I have ever seen.”