The UK Government has dismissed a call to reverse the devolution of responsibility for the British Transport Police to Holyrood after the force's planned merger with Police Scotland was branded "dangerous" and "reckless".

However, the Scotland Office will raise concerns, expressed by peers, with the SNP administration, after admitting it shares some of the "unease" at developments north of the border.

The controversial proposal to merge the two police forces has been criticised by the body representing BTP officers, saying it has produced a "collective sense of abandonment" among staff.

Rail unions are also opposed, fearing the merge could weaken safety standards as well as jeopardise 200 staff in Scotland and passengers.

But MSPs have already passed The Railway Policing Bill, which paves the way for BTP to become part of the national force in 2019.

In exchanges in the House of Lords on the merger, Lord Bruce of Bennachie, the former deputy leader of the Liberal Democrats, stressing how he was a passionate home ruler, said: “But we should also recognise that, as long as we are part of the United Kingdom - which the people of Scotland want us to be - devolution should be to enhance and bring Government closer…not to undermine the advantages of collective working across the United Kingdom.

“It seems to me that there will be circumstances where the transport police could be inhibited in their role in cross-border policing,” he explained.

Labour’s Lord Foulkes, also expressed concern at the proposed merger, saying the UK Parliament and Government should recognise “we have all made a major mistake in agreeing the responsibility for the BTP should be devolved to Holyrood”.

Stressing how he too was a long-standing supporter of devolution, the former Scotland Office Minister said: “But the way in which it is being dealt with by the Government in relation to the BTP is, quite frankly, dangerous, reckless and ought to be stopped.”

Noting how BTP was working perfectly well, the Labour peer went on: “Police Scotland is already a total debacle.

“The Chief Constable is on gardening leave. Officers have been suspended. The Chairman of the Scottish Police Authority has had to resign. Fortunately, a good new chair is taking over…Nevertheless, in spite of Susan Deacon taking over, it is wrong for the BTP to be incorporated into Police Scotland. It is wrong in terms of policing. It is wrong in every way,” he declared.

The Labour peer stressed it was not just a Scottish issue because “it will affect criminals in Scotland coming down to England and criminals in England coming up to Scotland on the railways and the BTP will not be able to deal with that”.

Lord Foulkes continued: “The Government should think again. They should withdraw this Statutory Instrument and go back to the Scottish Government and say that they have come up against intractable objects…and are having a change of mind in relation to devolving the British Transport Police. It is never too late to change your mind.”

Speaking in the second chamber’s Grand Committee, Lord Duncan, the Scotland Office Minister, responded to Lord Foulkes’s comment, saying: “Not a single person on these benches does not share his concern about some of the issues which seem to be unfolding; not for the sake of better policing or for better serving the people but, rather, for a narrower, more factional agenda. We all have a certain degree of unease about that particular aspect.”

Pointing out how the Smith Commission had agreed that responsibility for the BTP should be devolved, the minister noted: “I stress this matter was devolved to the Scottish Parliament and the Scottish Government; I do not believe that we can now revisit it in the fashion which the noble Lord would like, if I am being frank.”

But he added he would raise peers’ concerns “behind the scenes and with my counterparts north of the border”.

It is expected that the Lords will in the near future have a debate on the planned BTP and Police Scotland merger.