A row between Holyrood and Westminster over stop-and-search powers being exercised by British Transport Police has deepened with a strongly-worded attack by a Labour minister on the Scottish Justice Secretary.

Kenny MacAskill has been attacked by Tom Harris, the UK Transport Minister who is also Labour MP for Glasgow South, after the SNP minister had warned the extensive use of anti-terrorist laws for stop-and-search at Scottish railway stations was threatening to undermine good community relations with Scottish-based police. Mr Harris accuses the Justice Secretary of undermining morale and insists he should apologise.

Since the June 30 terror attack on Glasgow Airport, the British Transport Police (BTP) - the only force to be part of a UK-wide service - has carried out nearly 15,000 checks. Of these, 12% on people were counted as being on people from ethnic minorities. Over the past year, the other eight Scottish forces have used these powers fewer than 150 times, and last year only six times.

Mr Harris has written to Mr MacAskill in the strongest language used by a Whitehall minister against a counterpart in the SNP administration over the past seven months, saying it was "unacceptable and inappropriate for anyone in ministerial office to launch such an attack on police officers on the basis of hearsay".

He argued that the vast majority of rail travellers in Scotland feel reassured by the checks rather than threatened, and added: "Your attempts to invoke the prospect of discontent in community relations is cynical and irresponsible". Mr Harris demanded an apology.

He is to go on patrol with BTP officers in Glasgow tomorrow and warned Mr MacAskill: "I hope your ill-judged comments will not succeed in undermining the morale of the men and women of the BTP in Scotland or the confidence that the travelling public should rightly have in them."

Mr MacAskill responded that the public need an explanation why 230 BTP officers carry out so many checks when 16,200 other officers are involved in so few.