THERESA May has cast doubt on the SNP plan to merge British Transport Police and Police Scotland north of the border, calling for public safety to be put ahead of ideology.

The Prime Minister made the comment the day after the Scottish Government announced its controversial merger of the BTP and Police Scotland had been indefinitely delayed.

Mrs May queried “whether or not” the merger would go ahead.

The target date of April 2019 has been put off because of IT problems and the absence of the key Police Scotland officer on the project, Assistant Chief Constable Bernard Higgins.

The Scottish Government is keen for the merger to go ahead as soon as practical, despite the BTP strongly resisting the integration of its 200 officers into the single force.

A new study found two-thirds of BTP officers and staff in Scotland had considered quitting because of the planned merger.

The delay is expected to last six months to two years, however there is no set timetable.

At Prime Minister’s Questions, Tory MP Douglas Ross asked if the “pause” should be used to get “the best possible deal rather than these failed integration plans with an already struggling Police Scotland”.

Mrs May said the UK Government was committed to devolving control over British Transport Police to Scottish ministers, but suggested a full-blown merger might not be the result.

She said: “The number one priority must be the safety of the public as they travel.

“So we will work with the Scottish Government to ensure there is a smooth transfer of the British Transport Police to their responsibility.

“Whether or not the British Transport Police is merged with Police Scotland is of course a matter for the Scottish Government.

“It is a matter for the Scottish Government as to what they chose to do, but I would urge the Scottish Government they are putting the safety and security of people who are travelling first when they make that decision.”

Published by the Scottish Centre for Crime and Justice Research (SCCJR), the new study found 83 per cent of Scottish BTP staff opposed to plans to join Police Scotland.

Critics have previously cited safety issues as one of their main concerns, alongside a "lack of a business case" from ministers.

Despite opposition, legislation for the merger was narrowly passed at Holyrood last year, with the Scottish Government insisting it would make transport policing more accountable.

But the study, which this month surveyed 66 per cent of BTP’s Scottish workforce, found a "deep strain of scepticism, cynicism and opposition" towards the move.

Fears included uncertainty over terms, conditions and pensions, stress and low morale.

The study said: “Many respondents viewed the merger as politically or ideologically motivated, citing the lack of a robust business case as evidence.

"Respondents saw very few advantages for the BTP/A (British Transport Police Authority) or railway policing (most saw none) and a range of disadvantages.

"These included a loss of seamless border policing, a greater risk of delays, and financial costs."

While the majority of respondents opposed the merger, some cited advantages including the greater employment and development opportunities.

Researcher Dr Kath Murray said: "The decision to delay the merger is both sensible and welcome. As well as addressing the sizeable practical challenges, the merger will need buy-in from skilled railway officers and staff, which is yet to be secured.

"Our findings point towards a clear need for improved communication with BTP officers and staff about how integration will work in practice, and a better understanding of how the merger is affecting the professional and personal lives of BTP officers and staff."

A Scottish Government spokesman said: "We are committed to a no detriment policy and a triple-lock guarantee to secure the jobs, pay and pensions of railway policing officers and staff in Scotland.

"The integration of railway policing into Police Scotland will provide a single command structure, with seamless access to wider support facilities and specialist resources of the second largest police service in the UK, providing an enhanced service to the rail industry and travelling public.

"The Joint Programme Board overseeing integration have agreed to review the timetable, which will provide all partners with the opportunity to enhance the process of engagement, in particular with officers, staff and their representatives on key issues such as terms and conditions of service."