Merging British Transport Police (BTP) with Police Scotland could create an unnecessary "border" for officers, MSPs have been told.

BTP deputy chief constable Adrian Hancock said he would prefer to have Transport Police Scotland instead of the force being absorbed into Police Scotland, the sole option on which the Scottish Government is consulting.

He told the Scottish Parliament's justice committee on Tuesday the current setup assists "seamless" operations for counter-terrorist arrangements and cross-border incidents,

Mr Hancock fears a negative impact on lower-level incidents as he believes resources would be diverted from transport to more high-profile areas such as child sexual exploitation.

He said: "They are adding additional expense, additional controls, in effect creating a border for operational policing that we don't need to do.

"Why does BTP exist now if it is so easy for it to be absorbed into a geographic model?

"Forty-three forces aren't screaming to take responsibility for policing the railway... there's a real need for policing the railway in a different way."

He added: "There's a reason why our officers choose to join BTP - it's a very specialist policing role.

"They could have chosen to join Police Scotland but want to part of the very specialist policing function which we play."

Mr Hancock's concerns were echoed by British Transport Police Federation chairman Nigel Goodband, who told the committee BTP was solely focused on the specialised task of policing the "difficult environment" of the railways.

He said: "Bring that responsibility into another organisation like Police Scotland and it becomes another cog in a bigger wheel.

"I believe it won't have the same daily attention and the delivery of the same service that it receives at the moment because that is our sole responsibility.

"I think our service will be diluted in that the priorities of Police Scotland are totally different to what train-operating companies and the passengers want."

He warned officers would leave, particularly due to the uncertainty over terms and conditions and pensions.

Police Scotland assistant chief constable Bernard Higgins said there would be "massive transition issues" but claimed the current level of service could be maintained.

He said: "It's complicated but not insurmountable and operationally we could absolutely police the rail network in Scotland."

Mr Higgins said complex works were being carried out on the pensions and terms and conditions, and said all BTP officers would be given grandfather rights.

Conservative MSP Oliver Mundell questioned if the BTP officers would be used to "plug gaps" in Police Scotland and said the single force was in "crisis", which SNP MSP Fulton MacGregor denied.

Mr Higgins said the current level of BTP staff would not be cut and would be ring-fenced to work on the railways.

He said benefits of the merger would be in the volume of available resources and no requirement on BTP to request specialist services from Police Scotland.