One in 10 of Britain's overstretched soldiers and almost 7% of the RAF are in breach of the "harmony guidelines" established by the Ministry of Defence to limit the maximum time service personnel should spend away from home and family, The Herald can reveal.

Despite government denials that the forces are operating beyond their capacity to cope with simultaneous wars in Iraq and Afghanistan, almost 10,000 soldiers and 3000 RAF air and ground crew are currently exceeding the separated service limits.

Harmony guidelines recommend a soldier should do no more than 415 days away in any 30-month period. Latest Army statistics seen by The Herald state 10.3% of the Army is spending more than 415 days away from home base in a 30-month period.

This amounts to 9935 troops from an overall force of fewer than 100,000, with some specialist trades in constant demand on operations suffering more than most.

The RAF operates a slightly different system that allows for greater flexibility within Expeditionary Air Wings posted to combat zones.

Under harmony guidelines, an individual can be away for up to 140 days in a 12-month period before breaching the rules. The aim is not to deploy an individual for more than four months in every 20.

The current figure for RAF personnel spending more than 140 days away from the home base in a 12-month period is 6.7% of trained strength, or 2918 men and women.

The threshold for sailors in the Royal Navy is currently 660 days away in a rolling three-year period. This guarantees individuals a minimum of 435 days at the home base over three years' harmony time. Fewer than 1% of trained naval strength, a total of 59 sailors, are in breach of guidelines under this rule, despite long deployments in support of land operations in the Middle East and South Asia.

The National Audit Office reported last year almost half of those who left the armed forces since 2005 had done so because of the impact of service on family life (49%), while others reported the impact of too many deployments (28%).