Britain risks losing its senior influence within NATO if it fails to accelerate defence spending, a former top military commander has warned, amid growing concern among allies over the UK’s rearmament plans.

Admiral Sir Keith Blount, NATO’s former deputy Supreme Allied Commander Europe, said the Government must set out a “clear pathway” to meeting alliance spending targets or risk Britain slipping from a leading role to a “following nation”.

His warning comes as political uncertainty deepens over future defence spending plans, with Labour figures including Andy Burnham reportedly signalling support for increasing military budgets above the £13.5bn outlined in the delayed Defence Investment Plan.

The row has intensified tensions between senior figures and Downing Street over Sir Keir Starmer’s decision to push ahead with publishing the plan before stepping down in July.

Sir Keir has previously pledged to raise defence spending to 3 per cent of GDP by the next parliament, but has yet to explain how that target will be achieved.

Admiral Sir Keith, who retired last week after a 40-year naval career, said the current trajectory would leave the UK falling behind allies.

Speaking to The Times, he said: “The UK is a nuclear power. The UK still has this bulwark of reputation and influence that is clear for all the alliance to see.

“But if the other larger nations of the alliance outperform us in terms of meeting their capability targets, meeting the defence investment pledge, it is only natural the allies, as a completely rational body of nations, see those nations as the ones who deserve greater influence.”

He warned that without increased spending Britain’s position within NATO could be weakened, despite its long-standing leadership role within the alliance.

The UK has held NATO’s deputy commander role continuously since 1951, a position historically seen as a key source of influence alongside the United States, which holds the top military post.

However, defence sources have suggested that sustained underinvestment could open the door for other major European powers, including Germany or France, to push for greater leadership roles in the future.

NATO has set a long-term target for members to spend 3.5 per cent of GDP on core defence and 1.5 per cent on wider security-related spending by 2035.

Current UK plans would see spending reach around 2.68 per cent of GDP by 2030, with Treasury projections suggesting the 3 per cent threshold may not be met until 2034–35.

By contrast, German officials have indicated that Berlin could reach NATO’s combined 5 per cent target well before 2035, as Chancellor Friedrich Merz seeks to expand the country’s military strength.

The UK currently ranks near the bottom of NATO league tables for meeting rearmament commitments, placing 31st out of 32 members in terms of progress towards capability targets. Only Iceland, which has no standing military, is below it.

Air Chief Marshal Sir Richard Knighton, the head of Britain’s armed forces, recently warned that the UK must be prepared to go “toe to toe” with Russia.

The Government is expected to publish its Defence Investment Plan ahead of the NATO summit in Ankara, Turkey, on July 7.