US designates Nigeria’s militant Islamist Boko Haram group a terrorist organisation.
The move means US regulatory agencies are instructed to block business and financial transactions with Boko Haram.
It has also become a crime under US law to provide material support to the group.
Boko Haram wants to impose Islamic law in northern Nigeria and has been blamed for thousands of deaths.
The group began its insurgency in 2009, and targets both the military and civilians, including schools, and frequently clashes with the Nigerian armed forces.
While Boko Haram’s main focus is Nigeria, the US has cited links to the al-Qaeda affiliate in West Africa, and extremist groups in Mali.
The US state department has not formally announced its decision to brand the group a terrorist organisation.
Nigeria’s government declared Boko Haram and another militant group Ansaru as terrorist organisations in June, warning that anyone who helps them will face a minimum prison sentence of 20 years.
US’s decision will be welcomed by the Nigerian government and the Christian Association of Nigeria, which has long been campaigning for the US to declare Boko Haram a terrorist group.
The Obama administration had so far refused, fearing that it could give Boko Haram greater legitimacy in global jihadi circles.
Last year, top US diplomat for Africa Johnnie Carson said Boko Haram exploited popular discontent in northern Nigeria, and the government needed to tackle the political and economic grievances of the mainly Muslim population in the region.