The UK's armed forces face cuts to fill a record £17 billion black hole in the defence budget

Defence chiefs face making further cuts to the UK's armed forces to fill a record £16.9billion black hole in their finances.

Plans to buy weapons and equipment are 'unaffordable' according to auditors, making cutbacks inevitable.

A report by the National Audit Office, released today, has identified the largest budget deficit in defence spending ever recorded.

The biggest increases have been in the nuclear and naval programmes, up £54.6billion, according to the NAO.

Inflation has added £10.9billion to the costs of the Ministry of Defence's equipment plan, with the Treasury yet to allocate any extra funds.

Ministers are being accused of losing control of the defence budget at a time of conflict in Europe and in the Middle East.

The biggest problem is the UK's procurement system, say sources, as Britain routinely pays more and waits longer than its Nato partners for military equipment.

The NAO said: 'Forecast costs in March 2023 were £305.5billion, compared with the budget of £288.6billion. The plan is unaffordable.'

The MOD's accounts could be in even worse shape than the estimates as expensive commitments, such as upgrading the Challenger II tank, buying the latest air-to-air missiles and extending the lifespan of the Warrior infantry vehicle, have not been included.

The financial crisis is another concern for Defence Secretary Grant Shapps, who has faced criticism over his lack of military experience and knowledge.

John Healey, Labour's defence spokesman, said: 'Ministers have lost control of the budget and wasted public money. This risks leaving our armed forces without the equipment and troops they need to fight and fulfil our Nato obligations.'

The MOD said: 'This Government is working to deliver what our servicemen and women need to keep Britain safe.

'As a result we have significantly increased our spending on defence equipment to £288.6billion over the next decade.'