Rosemary Nelson suffered serious leg injuries in the blast in Lurgan, County Armagh, at about 1300 GMT.

It is thought a bomb had been planted in her car which exploded as she drove from her home.

Mrs Nelson has represented the residents of the Garvaghy Road in the continuing face-off over Orange Order marches in the town of Portadown.

In January she met Prime Minister Tony Blair at Downing Street about the marches.

She was earlier taken to hospital in a serious condition before doctors lost the fight to save her life.

It is not thought that anybody else was injured in the attack.

Police said no warning was given for the bomb and that no-one had claimed responsibility.

Ms Nelson is believed to be married with three young children.

Dara O'Hagen, the local representative of Sinn Fein, said the attack had been "carried out by experienced people".