Defence Secretary Philip Hammond rubbished claims by the Scottish National Party (SNP) that an independent Scotland would have 15,000 army personnel, saying they were living in "cloud cuckoo land".
The Conservative Cabinet minister questioned the SNP's maths, saying departmental figures showed they would need a bigger defence budget to deliver on the numbers.
He said: "The Scottish Government's so-called plans for the future Scottish defence force exist in cloud cuckoo land.
"The numbers simply do not add up.
"Our analysis shows that they would require something like 30% more than they are proposing to spend to deliver the force structure that they have outlined in their white paper.
"And, in due course, I should look forward to coming to Scotland, yet again, deconstructing, yet again, the rubbish coming out of the Scottish National Party."
Mr Hammond's comments were made in response to a question from SNP defence spokesman Angus Robertson MP, following a statement from the Defence Secretary on Armed Forces restructuring.
The Moray MP questioned the "disproportionate" cuts to services personnel, after Mr Hammond's predecessor, Dr Liam Fox, confirmed that between 2000 and 2010, the total UK reduction was 11.6%, compared to 27.9% in Scotland.
Mr Robertson had asked: "Will you confirm that personnel numbers are at a record low in Scotland - around 11,000 - significantly lower than the Scottish Government's plans for 15,000 after independence."