WASHINGTON (AFP) - The United States on Wednesday blacklisted Nigeria's Boko Haram group and an offshoot known as Ansaru as terror groups, bowing to months of pressure to move against the brutal insurgents.
"These designations are an important and appropriate step, but only one tool in what must be a comprehensive approach by the Nigerian government to counter these groups... to help root out violent extremism," the State Department said in a statement.
The Islamist insurgency has claimed thousands of lives since 2009, mainly in Nigeria's restive north-east, and caused international concern over its potential to spread across porous borders into other nearby safe havens.
"In the last several years, Boko Haram and Ansaru have been responsible for thousands of deaths in northeast and central Nigeria, including dozens of attacks on churches and mosques, targeted killings of civilians, and the 2011 suicide bombing of the United Nations building in Abuja that killed 21 people and injured dozens more," key White House homeland security adviser Lisa Monaco said in a statement.
"By cutting these terrorist organisations off from US financial institutions and enabling banks to freeze assets held in the United States, these designations demonstrate our strong support for Nigeria's fight against terrorism and its efforts to address security challenges in the north."
US officials accuse Boko Haram of links to Al-Qaeda in the Islamic Maghreb, while Ansaru is a splinter faction that earlier this year kidnapped and executed seven foreign construction workers.
Emergency rule in the northeast has largely pushed Boko Haram fighters from urban areas into the countryside over the last six months, but attacks have continued unabated.
The three Nigerian states under special measures - Yobe, Borno and Adamawa - share frontiers with Niger, Chad and Cameroon and the military has said that insurgents have struck in Nigeria, then fled across the porous borders.
"All of our assistance to Nigeria stresses the importance of protecting civilians and ensuring that human rights are respected. That assistance and these designations demonstrate US support for the Nigerian people's fight against Boko Haram and Ansaru," the State Department said.
The two groups were officially designated as foreign terrorist organisations, which will bar any Americans from assisting them as well as freezing all their assets in the United States.
President Barack Obama met Nigerian President Goodluck Jonathan in September and urged him "to pursue a comprehensive counterterrorism approach that uses law enforcement tools effectively, creates economic opportunity, and ensures that human rights are protected and respected", Ms Monaco said.