Outsourcing giant Serco has won the contract to operate sleeper trains between London and the Scottish Highlands.

The service, which is due to become operational next year will feature hotel-style cabins and luxury dining, the Guardian reports.

Scottish transport minister Keith Brown said the bid is a reflection of the Scottish government's plans to "transform this iconic Scottish rail service", but the award of the contract has been criticised by the RMT rail union.

It described Serco as "a company with a truly shocking track record in the delivery of public services", arguing it should not have been allowed to bid for the contract.

Serco estimates the 15-year deal will earn the company £800 million. The firm also operates the Northern Rail franchise in partnership with Abellio, and runs services in India and Australia, as well as the Dubai metro system.