A British junior defence minister is calling for London and Paris to develop and build a joint nuclear deterrent, The Guardian newspaper reported Saturday.

Armed Forces Minister Nick Harvey put the proposal to French defence experts at the ambassador's residence this week and told The Guardian that the plan was warmly received.

Historic rivals Britain and France agreed a deal in November last year to create a joint military force and share nuclear testing facilities, heralding an unprecedented era of defence cooperation.

The idea comes as Prime Minister David Cameron's coalition government implements eight percent defence spending cuts as it tries to get Britain's record deficit under control.

Britain currently has the capacity to have one of its ballistic missile submarines at sea, fully armed.

The coalition has deferred a decision on replacing Britain's nuclear weapons programme -- the Trident missile-based system on board its submarines -- until after the next general election, to be held by May 2015.

"The UK needs to revisit the case in the long term for the UK maintaining a permanent 24-7 at-sea capability. We pay an enormous premium to maintain this," Harvey said.

"It is quite feasible that we could continue with a permanent at-sea submarine patrol in conjunction with the French either with three British submarines as proposed to the current four.

"We could then rack up even bigger savings.

"We would be able to maintain separate command operations.

"It is unlikely we would face circumstances in which Britain would be faced with an external nuclear threat that would not apply to the French national interest at the same time.

"It is quite possible for the French and British to work together on research and development of replacement submarines, so nearly halving the development costs.

"Over a 25- to 30-year cycle... the potential is to save many billions of pounds (dollars, euros)," he said.

A decision on Trident has been put off as part of the coalition deal between Cameron's Conservatives and the smaller Liberal Democrats -- of which Harvey is a member -- who are against renewal.

In the defence agreement struck in November, Cameron and French President Nicolas Sarkozy signed two treaties which they said would allow them to remain global players while cutting defence budgets.

The deal includes the shared use of aircraft carriers from about 2020, a joint rapid reaction force of up to 5,000 troops deployable from next year and plans to share nuclear testing equipment by 2015.

The second treaty covers plans to share technology in the testing of nuclear weapons -- although officials stressed this would not see the two neighbours share nuclear secrets, nor the codes to their nuclear submarines.