The suspected leader of the Nigerian Islamist militant group Boko Haram is denying government claims that the group is involved in peace talks.

In a video posted on YouTube, Abubakar Shekau says group members have not sat down with government officials in a dialogue.

The video could not be independently authenticated.

Shekau also said Abul Qaqa, the group's suspected spokesman, is still alive despite claims from Nigeria's military that he was killed by security forces last month.

In addition, Shekau said security forces have begun to arrest the wives of members of the group. In the video, he threatened the wives of Nigerian government officials.

Boko Haram is believed to have several factions, which has confused government efforts to end the violence, either through security measures or negotiations.

The radical sect has been blamed for more than 1,400 deaths in Nigeria since 2010. Most of the bombings and shootings attributed to the group have taken place in northern Nigeria.

The group says it wants a hardline form of Sharia law imposed throughout the country.

Nigeria's population of 160 million is divided roughly between a mostly Muslim north and predominantly Christian south.