By Michelle Nichols
UNITED NATIONS, May 9 (Reuters) - The U.N. Security Council on Friday expressed outrage at the abduction of hundreds of Nigerian school girls in two attacks by Islamist militants, demanding their immediate release and threatening to take action.
Boko Haram kidnapped more than 250 girls from a secondary school in Chibok in remote northeastern Nigeria on April 14 and has threatened to sell them into slavery, while eight girls were taken from another village earlier this week.
"The members of the Security Council expressed their intention to actively follow the situation of the abducted girls and to consider appropriate measures against Boko Haram," the 15-member council, which includes Nigeria, said in a statement.
U.S. Ambassador to the United Nations Samantha Power said the U.N. Security Council should act quickly to designate Boko Haram as a terrorist group.
"We're working with Nigeria in the U.N. Security Council to secure urgently needed U.N. sanctions (on) Boko Haram," Power posted on Twitter. "Must hold its murderous leaders to account."
Boko Haram's five-year-old insurgency is aimed at reviving a medieval Islamic caliphate in modern Nigeria, whose 170 million people are split roughly evenly between Christians and Muslims, and it is becoming by far the biggest security threat to Africa's top oil producer.
The Security Council statement "demanded the immediate and unconditional release of all abducted girls still in captivity and further expressed their deep concern at statements made by the alleged leader of Boko Haram threatening to sell these girls as slaves."
It also condemned the latest big Islamist attack in Nigeria, the killing of 125 people on Monday when gunmen rampaged through a town in the northeast near the Cameroon border.
Several countries, including the United States, Britain, France and China, have offered support to Nigeria to help find the girls. British experts including diplomats, aid workers and Ministry of Defence officials arrived in Nigeria on Friday to advise the government on the search.
"The members of the Security Council welcomed the ongoing efforts of the Government of Nigeria to ensure the safe return of the abducted girls to their families, as well as international efforts to provide assistance to the Nigerian authorities in this regard and bring the perpetrators to justice," the statement said.
U.N. Secretary-General Ban Ki-moon said on Thursday that Nigerian President Goodluck Jonathan had accepted his offer to send a high-level U.N. envoy "to discuss how the United Nations can better support the government's efforts to tackle the internal challenges."
Ban said in a statement that he was deeply concerned about the fate of the girls and that "the targeting of children and schools is against international law and cannot be justified under any circumstances." (Reporting by Michelle Nichols; Editing by Leslie Adler and Nick Macfie)