Now aged 68, Mrs Rodgers said she would not contest her Upper Bann seat again because she wants to spend more time with her family.

But she said she would remain as the nationalist SDLP's deputy leader.

Party leader Mark Durkan described her decision as "a defining moment in politics in Northern Ireland".

The affection that she is held in by many, and the respect she enjoys among others, confirms that in both what she has done and what she represents

Alex Attwood SDLP chairman

Born in County Donegal, in the Republic of Ireland, Mrs Rodgers was first involved in politics during the Civil Rights Movement in the 1970s.

She was a founding member of the SDLP, having been encouraged into politics by former party leader John Hume.

She was the first woman to chair a political party in Ireland, but only became the SDLP deputy leader last year.

Mrs Rodgers, who has attracted praise for her handling of the foot-and-mouth crisis last year, said she was certain the SDLP would still do well in Upper Bann without her.

She said: "While not being a candidate myself, I will play my full role as deputy leader of the party within Upper Bann and throughout the other constituencies to ensure a large turnout of SDLP support and the return of a strong SDLP team to the next assembly."

She added that she had enjoyed her 30 years in politics, during which there had been "both difficult and good times".

'Affection'

Paying tribute to Mrs Rodgers, SDLP chairman Alex Attwood said: "From the Garvaghy Road to the farmyard, from civil rights to human rights, Brid represents the right person at the right time, doing the right thing.

"The affection that she is held in by many, and the respect she enjoys among others, confirms that in both what she has done and what she represents."

Mrs Rodgers was praised for her handling of the foot-and-mouth crisis

Mrs Rodgers' exit from the assembly will be the latest in a series of moves by the older founding members of the party to pull back from the front line and let younger members come through.

Last year, John Hume retired as party leader and resigned his assembly seat to reduce his workload because of ill health. His successor, Mark Durkan, became the youngest party leader in Northern Ireland.

Seamus Mallon gave up the SDLP deputy leader's position and Northern Ireland deputy first minister's post, which Mr Durkan now holds.