CAIRO (Reuters) - Sudanese opposition leader Sadiq al-Mahdi was arrested at his house in Khartoum on Saturday, his office manager told Reuters, days after the public prosecutor accused him of blaming the authorities for violence in Darfur.

Al-Mahdi, a former prime minister, is the head of the Umma Party, the most prominent party opposing President Omar Hassan al-Bashir.

"Two security officers came to al-Mahdi's office at 8:45 p.m. Sudanese time and arrested him without giving any reason," said Mohamed Zaki, al-Mahdi's personal assistant and office manager.

(Reporting By Khalid Abdel Aziz; Writing by Shadia Nasralla and Yasmine Saleh; Editing by Robin Pomeroy)