The group is named after a former policeman Mohammed Atef, aka Abu Hafs, of Egypt, who was a member of Ayman al-Zawahiri's al-Jihad al-Islami (Islamic Jihad).
The London-based Arabic language newspaper Al-Quds al-Arabi has received letters from this group, in which it has claimed responsibility for: There is no clearly defined stance on the existence of the Brigades can be discerned on the part of the jihadist radical community.
By and large, terrorist organisations have disregarded their statements and avoided including any reference in their own messages that might be construed as representing support for the Brigades or, conversely, a desire to dismiss them as a fraud.
Turkey claims that the Kurdish Hezbollah was responsible for the Istanbul bombings while the UN headquarters in Baghdad was blamed on Ba’athists.
Another previously unknown group calling itself the Lions of Al-Mufridun also has decided to claim credit for the Madrid attack, perhaps attempting to copy Abu Hafs al-Masri Brigades.