The systems would also be able to automatically tell the difference between vehicles, potentially diminishing the role that humans play in the gathering of intelligence.

Though the systems could, in theory, give confidence to military planners preparing a strike mission, it will also raise fears about machines being in a position to decide whether and when to use lethal force against an enemy.

Defence experts have been undertaking presentations to IT companies, explaining the type of equipment the military is looking for.

At one of the meetings in Cardiff earlier this month, they encouraged pitches for "automatic (assisted) target recognition" systems, specifically designed to identify people and vehicles from the air, or on the ground.

In particular, they asked for "detection and recognition of people and gestures in urban scenarios". Such sensors would be able to identify "face, gait and shape features", as well as "identify individuals or reacquire targets from their own signature".

Surveillance equipment can already identify vehicles, but the presentation explains that more sophisticated systems are needed because "current algorithms can be confused by camouflage, shadows, and clutter".

Ideally, the sensors would be able to differentiate between colours and have thermal imaging. The systems could be incorporated on UAVs – unmanned aerial vehicles, more commonly called drones.

The presentation in Cardiff was organised by the Defence, Science and Technology Laboratory, working with the Centre for Defence Enterprise. They are arms of the MoD that specialise in future technologies.

The military believes that there are small firms, not usually involved in defence work, that may be further ahead, or have better ideas, than the ones they are used to dealing with.

"It is our job to innovate, and to go beyond our standard suppliers," said a spokesman. "What we are looking to do is find out the maximum extent of what is feasibly possible. We need to engage with people who would not normally be involved in defence. Not just companies, but universities and academics too."

Chris Cole, who runs the Drones War website, said he was concerned about the focus on new systems that would give even more capability to UAVs, which have been used so controversially by the US to target suspected terrorists in Pakistan.

"While repeatedly insisting there is nothing controversial about the use of unmanned systems, the MoD is now combining drones with automatic target recognition technology in an attempt to seek out individuals on a so-called high value target list.

"Many will find this development extremely disturbing and inhuman. We call for proper public oversight and scrutiny of the growing development and use of armed drones by British forces."

Separately, the MoD has placed a 100-page document in the House of Commons library which sets out "the UK approach to unmanned aircraft systems".

It makes clear that UAVs will be an integral part of the UK's future weapons systems and could one day perform all of the tasks undertaken by RAF pilots. It also sets out the ethical and legal dilemmas that face the military.

The document states that there is a "general expectation across defence, academia and industry that unmanned aircraft will become more prevalent, eventually taking over all of the tasks currently undertaken by manned systems. This is strongly reflected in current government policy." Cutting costs and minimising the threat to personnel are the motivations for embracing new technology, it adds.

The document also makes clear that the joint strike fighter (JSF), which is due in service in 2020, could well be the last of its kind. "It is increasingly common to hear JSF referred to as the last manned fighter platform ... this may well be true.

"How soon we see the air power roles of attack and mobility and lift conducted by unmanned systems will be reliant on advances in technology, cost effectiveness and public acceptance."

Andrew Brookes, editor of The Air League, said: "By 2030 the mix between manned and unmanned in the air force will be half and half. Anything more than that is just an aspiration. My concern about the use of UAVs is that you should never give the politician an easy option to go to war. It should be the last resort, not the first. UAVs give them an easy option because lives are not being put at risk."