"UNCERTAINTY" around the merger with Police Scotland has sent morale plummeting at British Transport Police (BTP), a report has found.

HM Inspectorate of Constabulary in Scotland (HMICS) called for issues surrounding the impact on staff and officers' terms and conditions to be resolved at the "earliest opportunity".

The merger will take effect in April 2019 and the police inspector's overview of BTP warned the "scope and scale of the challenges and complexity posed by the transfer should not be underestimated".

The report said the full costs "have not yet been assessed" and stakeholders are unsure who will pay them, with detail about potential risks lacking. Meanwhile, officers said "uncertainty" about the changes had caused low morale.

It states: "This was particularly true of BTP police staff who fear there is no place for them at Police Scotland given that a significant proportion of police staff have left the organisation since its creation in 2013."

Derek Penman, HM Chief Inspector of Constabulary in Scotland, said: "It is not a merger of one complete organisation with another, but the partial extraction of a function from one organisation and its integration into another organisation.

"Throughout the transfer process, both BTP and Police Scotland must continue to deliver an effective service."

He added: "While both organisations provide a policing service, there are fundamental and significant differences in the way they operate.

"BTP is a police service paid for entirely by the rail industry and which has an ethos and commercial awareness which is quite distinct from other police forces."

Penman went on: "The officers and staff have been living with uncertainty regarding their futures for some time but have nonetheless remained committed to providing an effective service throughout.

"Issues relating to their terms and conditions and pension arrangements must be resolved at the earliest opportunity so as to provide them with information on which to base decisions about their future.

"Until those issues are settled, regular updates must be provided as to the progress being made."

The Scottish Government said: "Considerable progress has been made in ensuring the benefits of integration and improved accountability of transport policing to the Scottish Parliament are successfully delivered.

"Integration will ensure seamless access to wider support facilities and specialist resources, providing an enhanced service to the rail industry and travelling public.

"Pay and pensions of BTP officers and staff will be protected and we have recently set out to Parliament how we are giving effect to this commitment."