Sudanese opposition leader Sadiq al-Mahdi was arrested in Khartoum on Saturday. A former prime minister in Sudan's last elected civilian government, he is head of the Umma Party, the main opposition to President Omar Hassan al-Bashir, who ousted al-Mahdi in 1989.

Al-Mahdi's secretary, Mohammed Zaki said: "At 8:45 pm (1745 UCT) a number of state security officers came to the home of imam Sadiq Al-Mahdi with a warrant, and they arrested him." They did not give a reason for his detention.

The National Intelligence and Security Service (NISS) has the right to detain people for more than four months without judicial review. Sudan's judicial system is currently under fire for the death sentence imposed on a pregnant woman.

Al-Mahdi had appeared before prosecutors for questioning on Thursday after he reportedly accused a counter-insurgency unit of rape and other abuses of civilians in the war-torn Darfur region.

The Umma party is at the head of a dialogue process with other opposition groups and the president which may lead to a new, coalition government. The process has been opposed by the security services.

jm/slk (Reuters, AFP)