Khartoum - Sudan has rejected three presidential candidates, including  the only woman, for its first democratic elections in 24 years.

The ruling has raised further doubts about the presidential and legislative  elections after opposition accusations of fraud during registration and of  intimidation and vote buying by the ruling National Congress Party (NCP).

President Omar Hassan al-Bashir's NCP denies fraud and says the opposition is  unprepared.

Sudan's opposition has long complained the requirements for standing for the  mpresidency were too tough in Africa's largest country, devastated by decades of  civil war. Candidates must gather 15,000 supporting signatures from 18 of 25  states.

The only female candidate, Fatima Abdel Mahmood, leader of the Sudanese  Socialist Democratic Union, said the ruling was a conspiracy against women and  the party would appeal to the courts. "This is a form of discrimination," she  told Reuters.

The election system will require about 1,000 different ballot papers for at  least six different votes and has been called one of the most complex in the  world.