The Armed Forces are operating with at least 5,000 fewer men and women than are needed to meet Britain’s defence committments around the world, the goverment spending watchdog says today.

The highly critical report from the National Audit Office reveals that the Services have been operating beyond planned levels of defence for the past five years to keep troops in Iraq and Afganistan. It also shows that disillusionment among servicemen and women has increased to such an extent that 10,000 personnel are quitting the Forces each year.

In addition, the Deepcut barracks bullying scandal, along with the death toll in overseas campaigns, is putting off more and more potential recruits. A further hindrance is Britain’s obesity problem: the report shows that only one third of 16-year-olds would pass the body mass index (BMI) test for new recruits.

Liam Fox, the Shadow Defence Secretary, said yesterday: “This damning report confirms . . . that the gap between our commitments and resources is growing and putting unacceptable pressures on our Service personnel and their families.”

The three Forces are now 5,170 under strength, a shortfall of 2.8 per cent. The report, Recruitment and Retention in the Armed Forces, also says that they have deployed troops at higher levels than in defence assessments in overseas operations in each year since 2001. More than 8,000 troops are at present in Iraq, with 5,248 in Afghanistan and more than 900 in Bosnia.

It is also revealed that there are 88 different specialities, or “pinch points”, where staffing shortages are seen as critical. The report cites 70 per cent shortages in medical staff and a 50 per cent shortage in weapons systems operators.

As a result, service personnel are working longer hours and spending more time away from their families. As many as 14,000 army personnel (14.5 per cent) had breached Ministry of Defence guidelines by spending too much time away from home in the past 30 months.

In some areas where the shortages were particularly acute, up to 40 per cent had breached the guidelines. The report claims that many men and women are quitting because overseas deployments leave them with too little time with their families.

The audit office says that the number of those leaving the Services early has increased slightly in the past two years, with 9,200 leaving last year before their period of engagement was up.

A survey of those who had recently left showed that 49 per cent did so because of the impact on family life, 28 per cent cited too many deployments and 32 per cent blamed poor quality of equipment.

Recruitment has been hit by Iraq and by stories of bullying at Deepcut. “The Army’s research found that 42 per cent of parents would be less likely to encourage their children towards a career in the Army because of operations in Iraq, while 27 per cent said they were put off because of events at Deepcut,” the report said.

However, the audit office re-commends that the Ministry of Defence spend its money on retaining staff rather than recruitment. It argues that it costs £74 million to retain 2,500 people for another year, compared with £189 million to recruit and train the same number.

Last week Bill Jeffrey, Permanent Secretary at the MoD, admitted to the Commons Defence Committee that having 13,000 troops in two long-term campaigns breached the Government’s own policy on the maximum commitment of the Armed Forces to overseas operations.

Derek Twigg, the Defence Minister, denied that the forces were overstretched. “We do understand the impact that frequent operational tours have on serving personnel, their friends and families, and we have recently announced improvements in pay and benefits for those who are deployed on operations.”