Sidi Ould Walid said his brother was released after renouncing his ties to the terror network and condemning the September 11, 2001 attacks.

Hafs refused to be interviewed or to be filmed as he left the prison.

On militant forums, jihadists exchanged congratulations over the release.

Hafs was an adviser to Osama Bin Laden who helped form the modern al-Qaida by merging Bin Laden’s operation with Ayman al-Zawahri’s Islamic Jihad.