|Abubakar Shekau, Boko Haram's leader, accuses the government of staging a series of attacks on Muslim civilians
Boko Haram, the Nigerian Islamist group, has denied government reports that its spokesman was arrested, but confirmed another senior member of the faction was detained instead.
In a phone conference with journalists in the northeastern city of Maiduguri on Thursday, Boko Haram said that Abu Dardaa, the group's head of "public enlightenment", was arrested and not spokesman Abul Qaqa.
The man speaking on the phone claimed to be Abul Qaqa himself, but his voice reportedly sounded different from previous such conferences in which the purported spokesman has claimed responsibility for scores of deadly attacks.
There has also long been speculation over whether those going by the aliases Abul Qaqa and Abu Dardaa are the same person.
"We want to react on what security agents said regarding the arrest of one of our members," the man said.
"The person that was arrested was Abu Dardaa and not Abul Qaqa. I am Abul Qaqa. Abu Dardaa is the head of the 'Lajina', the department of public enlightenment, and not the spokesman."
A senior secret police official, speaking on condition of anonymity, said it appeared the person who issued the comments was indeed connected to Boko Haram, but he dismissed the statements as propaganda.
"It is no surprise they are making this ridiculous claim," the source said.
"Abul Qaqa is part of the 11-member Shura council, the sect's decision-making body, and his arrest is a serious setback to the sect."
Security sources said on Wednesday that a suspect believed to be the person who goes by the alias Abul Qaqa had been arrested. Authorities have not officially confirmed his detention or his identity.
The man purported to be Boko Haram's spokesman alleged that Dardaa was arrested when he was sent to the northern city of Kaduna for negotiations with government officials.
Al Jazeera's Yvonne Ndege, reporting from Abuja, Nigeria's capital, said that the speaker told reporters "this individual was on the way to start negotiations with the Nigerian government around a peaceful settlement to the Boko Horam crisis. But then the Nigerian government turned the tables on him and arrested him on the spot."
Ndege continued: "He said that this was a betrayal that would undue peace in Nigeria and that the arrest and detention of the group's members would not deter them from further attacks."
Boko Haram has earlier said, "The arrest of Abu Dardaa is an outright deception and betrayal by the Nigerian government and security agents. They proclaim dialogue but are doing the opposite."
With authorities unable to stop attacks blamed on Boko Haram, there have been growing calls for dialogue to bring an end to the violence.
Boko Haram's deadliest attack yet occurred on January 20, when coordinated bombings and shootings killed at least 185 people in Nigeria's second-largest city of Kano.
The group also claimed responsibility for the August suicide bombing of UN headquarters in Abuja that left at least 25 people dead.
Boko Haram accuses government forces of frequently oppressing and attacking civilians in the country's predominantly Muslim northern regions for years.