TRANSPORT Minister Humza Yousaf has made a fresh plea for powers over Scotland's rail infrastructure to be devolved to Holyrood.

He made the call in a letter to the UK transport secretary Chris Grayling.

It was prompted by Mark Carne stepping down as chief executive of Network Rail, which owns the UK's rail infrastructure.

Yousaf said Grayling should appoint a separate chief executive to take charge of services in Scotland, as well as a UK-wide replacement.

Holyrood has power over the awarding of the franchise to run ScotRail services. However powers over rail infrastructure, including management of train tracks, are reserved to Westminster.

Yousaf maintained this left Holyrood with no influence over a significant part of the rail network in Scotland when half of the rail performance faults are related to infrastructure.

He said there was a need for the greater devolution and better governance arrangements for Network Rail in Scotland.

Yousaf said: "There is a lack of accountability of Network Rail to Scottish Ministers and to our Parliament under the current arrangements.

"Strengthened and improved governance arrangements for the Scotland route are a necessity. I would therefore request that a separate chief executive appointment for Scotland be considered."

In response, a Department for Transport spokesman said: “Network Rail and the Department for Transport will be working closely with the Scottish Government to take account of the views of Scottish ministers ahead of the appointment of the new chief executive.”