Peter Law stood against the Labour candidate, Maggie Jones

Mr Smith, who backed his colleague's decision to stand against Labour as an independent, said no matter how ill he was, Mr Law was determined to "stand up for the people of Blaenau Gwent".

He said: "He was determined that people were going to have the right to choose a candidate of their choice and that choice wasn't going to be taken away from them".

Referring to his protest about an all-women shortlist in his constituency, he added: "Peter was really angry, I know, that that was being taken away from them.

Despite his recent estrangement from the Labour Party which he served for most of his life, Peter still had many friends who will be saddened by his death Welsh Secretary Peter Hain

"And no matter how ill he was, he was determined that wasn't going to happen and it didn't happen and that's down to Peter."

Tributes were paid on Tuesday across the political divide.

First Minister Rhodri Morgan said: "Whatever our political differences over the past year or so, we will always think of Peter's decades of public service to his local community and to the wider Wales.

"We will always remember him for his robust and rumbustious contributions to our debates in the assembly. He was armed with a rapier wit but invariably delivered with a smile.

Welsh Secretary Peter Hain said: "Despite his recent estrangement from the Labour Party which he served for most of his life, Peter still had many friends who will be saddened by his death."

'Outstanding figure'

Welsh Tory leader Nick Bourne said: "With his passing, political life in Wales is the poorer.

"Peter was one of the most principled and courageous people I have ever known. I will miss him immensely."

Mike German, leader of the Liberal Democrats in the Welsh assembly, described him as "a dogged fighter to the end".

Peter was Blaenau Gwent and the people of Blaenau Gwent belonged to Peter - he was a man of the streets Political agent Dai Davies

"I will remember him for his determination and great warmth and friendliness which was apparent to all those in his constituency," he said.

Plaid Cymru leader Ieuan Wyn Jones said Mr Law "was one of the outstanding figures of post-devolution Wales".

"He was always prepared to speak his mind, and was not afraid to depart from the party line in the interests of his constituents," he added.

Don Touhig, MP for neighbouring Islwyn Don Touhig, who had appealed to Mr Law not to stand against Labour, said he was "deeply saddened".

'Courageous man'

"Peter and I had our differences but we still enjoyed a joke and were still friends and I believe that's important," he said.

Peter Law, here with his wife Trish, became an MP in 2005

"Peter, like me I think, is very rooted in the valleys and the people of the valleys. He understood them, he worked with them, he worked for them.

Paul Flynn, MP for Newport East, said: "He will be remembered as a man who stood up for his beliefs.

"I have sweet memories and respect for a very courageous man."

He said: "He had a talent as a politician and was one of the best speakers in the assembly in my mind, but he didn't have enough time to make an impression in Westminster."

Mr Law's political agent, Dai Davies, said: "I have never ever in my 25 years of trade union and political life met anyone, that represented people at any level, in the way Peter did.