"I urge the government to take swift and effective measures to reward the commitment of those doctors that remain, encourage those that have left to return, and to recruit new doctors to the services," he said.
A total of 9,144 were in the "medically downgraded" category, the party's defence spokesman Menzies Campbell has revealed.
He was quoting a letter from Junior Defence Minister Dr Lewis Moonie which said that 9.5% of the Army's strength were in the category along with 5.9% of the Royal Navy and 7% of the RAF.
He highlighted the accident and emergency service which only has 13% of the required number of consultants.
"These statistics are profoundly disturbing," Mr Campbell said.
"Britain's armed forces are already undermanned and overstretched. If 10% of the Army is unfit, this puts further pressure on other servicemen and women."
'Heavy cuts'
Mr Campbell said the health and well-being of service personnel was of the utmost importance.
"Those who risk their lives for their country are entitled to expect the best medical care."
He said the armed forces were still suffering from heavy cuts by the last Conservative government.
"It is about time this government put things right," Mr Campbell said.
Dr John Ferguson, chairman of the British Medical Association's armed forces committee, said the DMS were woefully understaffed.
"I urge the government to take swift and effective measures to reward the
commitment of those doctors that remain, encourage those that have left to
return, and to recruit new doctors to the services," he said.
Dr Moonie said the government recognised the serious manpower shortages in the DMS and its impact on medical operational capability.
"Work is in hand on a range of measures to improve recruitment and retention," he said.
"A key element of the future strategy is the creation of the Centre for Defence Medicine which is to open in Birmingham in April 2001.
"This will be a centre of excellence in military medicine, which we believe will help in recruiting and retaining medical personnel," he said.
"We recognise there are no quick fixes; doctors and nurses cannot be created overnight but we believe we are on the right track."