THE beleaguered boss of the firm running Scotland's railways has quit, our sister publication The Herald understands.

Phil Verster is to leave his post as managing director of ScotRail just 18 months into the post, with sources claiming he is to move to a new role within the railway industry.

The surprise departure comes just days after the publication of figures which showed it to be the second-best performing rail operator in Britain and following the South African's admission that attacks on under-fire ScotRail had become personal.

The claims came on the back of the publication in the media of details of his contract. ScotRail is expected to announce the departure later today.

Mr Verster has also been at the centre of a bruising rows over the performance of the country's railways in the past year, with the network hit by the impact of the programme to modernise it as well as several high-profile incidents leading to major delays.

In recent months, Scotland's transport minister Humza Yousaf has threatened to put in a public bid for the ScotRail franchise if performances did not improve.

And in recent weeks details of the tax-payer funded relocation package he received to move to Scotland were made public.

Mr Verster is understood to have expressed surprise in private at what he believed to be the over-politicisation of the rail industry in Scotland in recent years.

A source said: "You need to ask why he has decided to move on, even if its to another big job. He's only been in the post 18 months."

Before joining the ScotRail Alliance, the joint operation between Abellio, the Dutch operator of the ScotRail franchise, and publicly-owned Network Rail, Mr Verster held a number of major positions within the trains industry.

He had been route managing director of Network Rail's second largest route, London North East, which includes the East Coast Main Line between London and Scotland.

At the time of his appointment Abellio credited him with "the implementation of continuous improvement, to drive cost benefits on the East Coast route and that, and his record in safety improvement, made him the ideal candidate for the role".

Prior to joining Network Rail in 2012,Hewas deputy chief executive officer at Irish Rail and before that engineering director at a London-based train operating company.