A sharp drop in the number of Army Reserve soldiers has called into question Government plans to put the part-time force at the centre of the future of the Armed Forces.
The number of reservists has decreased significantly over the past three months, according to the figures released in the Ministry of Defence's Quarterly Personnel Report.
It comes as the MoD is attempting to grow the Reserve Force to 35,000 as part of coalition reforms, which will see regular army troops reduced by 20,000 by 2015.
The strength of the Army Reserve has fallen by 1,630 personnel, the MoD's latest quarterly figures show.
Between the end of July and September this year, 4,090 people joined what is referred to by the department as the Reserve Population but 5,650 left.
Commenting on the poor figures, Defence Secretary Philip Hammond said: "We have always said that growing the Reserve Forces to 35,000 by 2018 would be challenging but achievable.
"We are now less than two months in to a five-year recruitment drive for the Army Reserve and the Chief of the Defence Staff and I remain confident that we will meet our target."
Mr Hammond told the House of Commons earlier this month there had been 1,576 applications to join the Army reserve in the first four weeks of the campaign.
Shadow defence secretary Vernon Coaker said the drop in the Army reserve numbers posed "major questions" about the Coalition's planned reforms.
He added there were concerns over the Government not publishing reserve recruitment figures, suggesting Mr Hammond had "something to hide".
Mr Coaker said: "We have no way of knowing whether the Government is on course to meet its own targets. A previous report showed that the Government fell far short.
"The failure to provide transparency on its own figures can only lead to the conclusion that the Defence Secretary has something to hide."
Replying to Mr Coaker's claims, an MoD spokeswoman said: "The decision not to publish additional data today was one taken by the National Statistician and Defence Statistics, an independent body over which the MoD quite rightly has no control."
The figures issued by the MoD are better if only trained reservist personnel are taken into account - that results in a net loss of 30.
The total strength of the Reserve Force, which includes the Maritime Reserve and Royal Auxiliary Air Force is 21,870, of which the Army Reserve makes up 19,090.
A total of £1.8bn has been committed over 10 years to supplement training and equipment for reserve soldiers in order that they receive the same level of kit as their regular counterparts.
The number of overseas training exercises will increase to 22 per year from seven last year. But this, and any operational deployments, would put increased strain on small businesses.
To compensate for that, the MoD is offering a financial package to any companies losing staff to reservist duty. This would allow them to recruit temporary replacement workers.