FACTBOX: Candidates for Pakistan's presidential vote

(Reuters) - The official candidates list was announced on Saturday for a September 6 election to replace Pervez Musharraf, who quit on August 18 under threat of impeachment as president of nuclear-armed Pakistan.

Under Pakistan's constitution members of the country's four provincial assemblies and the two-chamber national parliament elect the president.

Here are some facts about the three main presidential candidates:

ASIF ALI ZARDARI

* Former Prime Minister Benazir Bhutto's widower and political successor, Zardari was thrust into the centre of politics by his wife's assassination on December 27, and then to the centre of power after their Pakistan People's Party won the most seats in a February 18 election.

* Born in the southern province of Sindh to a land-owning family, the telegenic Zardari, 55, has long been controversial.

* He served as a minister in his wife's second government in the 1990s, and was a senator until 1999, but was accused of getting kickbacks on government deals and earned the nickname "Mr Ten Percent".

* Despite spending altogether 11 years in prison on charges of corruption and murder, Zardari, who has denied all accusations and was never convicted, was released on bail in 2004.

* His Pakistan People's Party (PPP) has also denied charges of mental instability, saying Zardari was tortured in prison and as a result had been under mental stress and had had a heart problem, but was never mentally ill.

* Last year, Musharraf granted an amnesty to Bhutto, Zardari and other PPP leaders from graft charges under a power-sharing deal with Bhutto.

* He married Bhutto in 1987 and they had three children -- two girls and a boy.

* Analysts say Zardari should have enough electoral college votes to win.

SAEEDUZZAMAN SIDDIQUI

* Siddiqui is a former judge, nominated for the post of president by former Prime Minister Nawaz Sharif's party, the Pakistan Muslim League (Nawaz), which placed second to the PPP in February elections.

* The soft-spoken Siddiqui was a Supreme Court judge when he ruled in favor of then Prime Minister Sharif in a confrontation with the judiciary in 1997.

* Siddiqui lost his job as a Supreme Court judge after then army chief Musharraf overthrew Sharif in a 1999 coup and demanded an oath of allegiance from members of the judiciary.