STEVEN Purcell, the leader of Glasgow city council and one of the rising stars of Scottish politics, announced his resignation today.
• Mr Purcell has been a highly visible council leader
The leader of Scotland's biggest local authority tendered his resignation at a special meeting of the council's Labour group.
His deputy, Jim Coleman, is to take up the position until councillors elect a permanent replacement.
Mr Coleman said today: "The Labour group has accepted Councillor Purcell's resignation as leader.
"What's important now is that the people of Glasgow know that, as far as the council is concerned, it's business as usual.
"The administration will continue to provide leadership for the city as a whole. As always, our focus is firmly on Glasgow's priorities."
Mr Purcell's colleagues were said to have been informed of his intention to stand down late on Monday afternoon.
It us understood that Mr Purcell, who had been tipped as a future leader of the Labour party, stood down "for personal reasons" after friends and family raised "concerns about his health".
The Herald newspaper cited a statement issued last night, saying that those around Mr Purcell were "deeply concerned about the stress levels he had been displaying".
The statement said that there was "enormous pressure" on Mr Purcell over issues like the recent expenses scandal at the Strathclyde Partnership for Transport and the preparations for the 2014 Commonwealth Games in Glasgow.
Mr Purcell, 37, was made council leader in May 2005 and has been widely tipped to land the nomination for any of the vacant Scottish seats at Westminster.
Earlier, a Scottish Labour Party spokesman said: "We respect Mr Purcell's statement indicating that he intends to resign and so the Labour group on the council will meet today to ensure that all its business can be properly carried out.
"We hope Steven makes a full recovery."
Mr Purcell was not at the short meeting of the Labour councillors, in which they were told of his decision to step down.
He did not contact the council directly and has not been in the City Chambers since Friday.
Proceedings to elect a new permanent leader will begin later this year, probably after the general election.
Speaking after the meeting, Mr Coleman said: "It was a great shock. We didn't know Stephen was under such pressure. I never picked anything up.
"All we can do is wish him a speedy recovery. It is very sad for Glasgow. Stephen Purcell did a lot of good work for Glasgow.
"It shows the stress that people in these positions are under.
"My job here from today is to continue the good work he started and to make sure it is business as usual for Glasgow. There are big challenges ahead but we will continue to deliver the agenda for change."
Mr Purcell was 32 when he was elected to the post of council leader in 2005.
In his time in the job he played a high-profile role in helping to bring the 2014 Commonwealth Games to Glasgow but also clashed with First Minister Alex Salmond over the Scottish Government's decision to cancel the Glasgow Airport Rail Link project.
He was first elected to Glasgow City Council in May 1995 and served as the council's convener of development and regeneration services and then as education convener, before becoming leader.
It is reported Mr Purcell, who left his wife and came out as gay in 2006, will remain as a councillor in Glasgow.
Mr Purcell's spokesman Jack Irvine said the former leader had been "under enormous pressure".
He agreed to visit doctors after close friends and family became concerned for his health and "the stress levels he had been displaying".
"Steven agreed to seek medical help immediately and subsequently he is now under doctor's orders," Mr Irvine said.
"He would hope to get back in to active politics in the next few weeks and months. He hopes the people of Glasgow would appreciate what he has tried to do for the city he loves."
A spokesman for First Minister Alex Salmond paid tribute to Mr Purcell.
Mr Salmond's spokesman would not comment on his reasons for standing down as leader, saying that was a "private matter".
But he said: "We would pay tribute to the contribution he has made to Glasgow, particularly the partnership that the Scottish Government and Glasgow City Council have been involved in to secure the Commonwealth Games, and to plan for a fantastic legacy from the Games for Glasgow and the whole of Scotland.
"The First Minister and Councillor Purcell have worked very effectively together in the best interests of Glasgow in the preparations that are well under way to ensure we have a fantastic Games and a lasting legacy."
Mr Purcell was named as Councillor of the Year at last year's Scottish Politician of the Year awards.
He was given the honour for his role in delivering the Commonwealth Games to the city and a guaranteed "living wage" to thousands of Glasgow workers.