Abuja- Nigerian authorities have arrested a man believed to be a spokesman for Islamist group Boko Haram, which has claimed responsibility for scores of deadly attacks, security sources said Wednesday.

Two security sources said on condition of anonymity that a person suspected to be the man who goes by the alias Abul Qaqa had been arrested.

A third security source said officers were still trying to ascertain his identity, while secret police spokeswoman Marilyn Ogar said she could not confirm the arrest.

"We made a big success with the arrest of the Boko Haram spokesman that goes by the name Abul Qaqa," a secret police source told AFP.

A senior police source said he had "received information of the arrest of the Boko Haram spokesman ... He has been held for questioning."A third security source said "agents want to be sure that it is actually the spokesman of Boko Haram. They are still trying to ascertain that."

The man who goes by the name Abul Qaqa has claimed to speak on behalf of Boko Haram on numerous occasions, including to claim responsibility for scores of attacks in Nigeria, Africa's most populous nation and largest oil producer.

Its most deadly attack to date occurred in Nigeria's second city of Kano on January 20, when coordinated bombings and shootings killed at least 185 people. A man calling himself Abul Qaqa claimed that attack on behalf of Boko Haram.

The purported spokesman has regularly held phone conferences with journalists in the northeastern city of Maiduguri, Boko Haram's base.