The European Union has told Britain it will have to pay if it wants its defence firms to compete in a lucrative rearmament fund, reports say. British companies are not expected to get an automatic right to participate in the fund, despite a new EU-UK defence and security partnership expected to be unveiled later this month, according to The Times.

A European diplomat told the newspaper British arms firms will have to “pay to play” to bid for contracts from the fund. “Some countries want the UK in the game and others, the French are not enthusiastic,” the diplomat said. The move will likely be seen as a blow to Sir Keir Starmer as he strives to reset relations with the EU following Brexit.

The European Commission announced plans to loan up to €150 billion (£128 billion) to lend to bloc nations in March as part of a rearmament push amid concerns over the threat posed by Russia and US commitment to European security.

"We are living in the most momentous and dangerous of times,” President Ursula von der Leyen said.

"We are in an era of rearmament. And Europe is ready to massively boost its defence spending."

Non-member states, including the UK, were excluded from securing contracts under the Security Action for Europe (SAFE) fund, unless they signed a defence pact with Brussels.

But after pressure by France, British firms will not automatically be allowed to take part despite the pending EU-UK partnership set to be announced at a summit in London, The Times reports.

It is claimed access will be subject to a separate negotiation and conditions, which will include a financial contribution by the UK.

Details of the “pay to play” could reportedly take months to finalise and there will be restrictions on which British-made equipment or weapon systems are eligible.

UK defence giants such as BAE Systems and Babcock had reportedly been lobbying to access the fund.

Arms firms within the European Economic Area, plus Switzerland and Ukraine, will reportedly get automatic access to funded projects.

Britain is ramping up its production of munitions as it moves to reduce its reliance on the US and France.

Defence Secretary John Healey said the defence industry "is the foundation of our ability to fight and win on the battlefield".