On 22 November 2012, peers approved a motion to outlaw the Nigeria-based al-Qaeda group, Ansaru, a suspected terrorist organisation.
The draft Terrorism Act 2000 (Proscribed Organisations) (Amendment) Order 2012 was approved unopposed with a vote.
The motion is used to add terrorist groups to the Home Office list of proscribed organisations. Before a group can be added to the list, it must be debated in both Houses of Parliament.
Ansaru was formed in February. It is a breakaway faction of Islamist militant group Boko Haram - responsible for the 2011 bombing of UN headquarters in Abuja.
The statement said that "having carefully considered all the evidence the home secretary firmly believes that Ansaru is concerned in terrorism".
Labour commended the government on its "speedy action" and said it was satisfied Theresa May, the home secretary, was justified in adding the group to the list.