Brian Wilson has been an MP for more than 15 years

The MP for Cunninghame North had repeatedly denied rumours that he was considering quitting politics.

But Mr Wilson, 55, has now confirmed that he will not be standing for re-election to the Ayrshire constituency.

Prime Minister Tony Blair paid tribute to Mr Wilson as a "first-class minister and politician and a good friend".

Mr Blair added: "He has always put forward the case for New Labour with skill and courage.

"He has done an excellent job in the posts he has held and I wish him every success in whatever he chooses as his future career."

I've done my stint, I hope I've made a decent contribution and it's time to move on Brian Wilson

Mr Wilson, who announced his decision in a letter to his local constituency party, said it was based on personal rather than political reasons.

He said that with a new constituency being created through boundary changes, it was the right time to stand down and "give someone else the opportunity to serve as an MP from the outset".

He also paid tribute to his local party, saying: "The evidence of what can be achieved by people working together for the common good can be seen in every part of the constituency, just as the benefits of a Labour government can be found in every home, hospital and classroom."

'Massive contribution'

Mr Wilson told the BBC's Good Morning Scotland programme: "I've done my stint, I hope I've made a decent contribution and it's time to move on."

The former minister has had a long history of political activism

Scottish Labour Party general secretary Lesley Quinn praised Mr Wilson's "commitment and determination to improve the lives of ordinary people".

"Brian has made a massive contribution to the Labour government," she added.

Mr Wilson, a father-of-three, was educated in Dundee and Cardiff and founded the West Highland Free Press.

Born in Dunoon, he was the editor and publisher of the left-wing weekly newspaper, before becoming the MP for Cunninghame North in 1987.

Newspaper roots

He served in both the Scottish Office and the Scotland Office, and became energy minister in 2001.

The MP announced that he was leaving the government in 2003 to pursue "different challenges".