The chairman of Scotland's largest transport authority has resigned following questions over expenses.
Alistair Watson, who is also a Glasgow Labour councillor, stood down from Strathclyde Partnership for Transport (SPT) on Monday for health reasons.
It comes after documents obtained under Freedom of Information showed SPT officials claimed more than £100,000 between 2006 and 2009.
Financial watchdog Audit Scotland has been asked to investigate the claims.
A statement from SPT said: "SPT can confirm that our Councillor Alistair Watson has resigned as chair of SPT with effect from today.
"Alistair is well respected as a transport expert and his extensive knowledge of the transport industry will be sorely missed by the organisation.
"Councillor Watson had heath problems last year and he has again been advised to reduce his work load. The election of the new chair of SPT will take place at our next Partnership meeting on Friday 26 February."
The complaint to Audit Scotland over expenses at SPT was lodged by Glasgow SNP Councillor Graeme Hendry on 11 February.
He said: "There are real questions to be answered about the management of SPT.
"This resignation must mark the start of a thorough investigation into the practices at SPT - particularly among management and board members when it comes to expenses, travel and consultants."
Mr Watson began work in the railway industry in 1976 and worked as a train driver with ScotRail for 24 years. He was first elected to local government in 1995-96.
He was chair of the West of Scotland Transport Partnership from 1999 until 2003 and has been a member of SPT (formerly Strathclyde Passenger Transport Authority) for the past 15 years.
SPT has two vice chairs - Davie McLachlan from South Lanarkshire Council and David Fagan from North Lanarkshire Council.
They will both be in charge of the organisation until a new chair is elected.