The Conservatives said the system would have three components - new advanced radar systems, upgraded command and control systems to integrate information from across Britain's defences and rapidly decide a response, and new interceptor missiles as well as counter-drone capabilities.

The three-tiered design of the proposal is similar to the British Army's current Sky Sabre, external air defence system.

This system - which can intercept munitions and aircraft as well as integrate with wider air defences - was deployed by the UK to the Middle East earlier this year for defensive action against Iranian attacks.

Sidharth Kaushal, a senior fellow at the defence and security think thank RUSI (the Royal United Services Institute), said £10bn would "probably cover" what the UK "actually needs" including horizon radar and more E7 aircrafts.

"In contrast, if what the Conservatives envision is a truly Israeli style multi-layered missile defence system, £10bn probably wouldn't get there," he said.

"But that system would also be quite superfluous, arguably."

Prof Steven Barrett, CEO of Cambridge Aerospace which has been developing interceptor missiles, told the BBC £10bn was a "significant commitment" but the exact cost of the project would depend on the detail of the Conservatives' proposal.

He said that it would not be practical for the system to defend "every square inch" of UK territory and a more plausible set up would cover "significant parts of the population in key high density areas".

He also said there needed to be a focus on protecting critical national infrastructure, adding that a" huge amount of damage" could be done if data centres used by transport and health systems came under attack.

In his speech at the conference in Birmingham, shadow defence secretary James Cartlidge will say: "With a £10bn budget, this would be one of Britain's most significant military programmes since the cold war.

"But one that is totally necessary because of the threats we face."

Defence Secretary Wes Streeting said in response: "They [the Conservatives] cut the Army to its smallest size since Napoleon and left a £17bn hole in the equipment plan.

"Their own defence secretary, Ben Wallace, admitted our Armed Forces had been 'hollowed out and underfunded'."

Prime Minister Andy Burnham has been under pressure to set out how he will reach Nato's 3.5% of GDP spending target by 2035, up from an estimated 2.6% this year.

The current Labour government's Defence Investment Plan includes more than £350m to double the number of Sky Sabre systems operated by the British Army, with ground-based air defence sitting alongside air and maritime capabilities.