A court has convicted a Nigerian member of the Islamist militant group Boko Haram of killing three people in a bombing and sentenced him to life in prison.

The Nigerian court said Friday that during the April 2012 attack 34-year-old Umar Mustapha threw a bomb at a media house in the northern city of Kaduna.

In what appeared to be a coordinated operation by Boko Haram, a suicide bomber rammed his car into the office of the Thisday newspaper in the capital, Abuja, at about the same time, killing six people.

The court said Mustapha was overpowered by a "mob" of civilians as he fled the scene of his attack.

He is the only person who has been arrested in connection with the two assaults.