Boko Haram militants have killed a midwife who was kidnapped in an attack in remote northeast Nigeria more than six months ago, the Red Cross said on Monday.The humanitarian agency condemned the "tragic killing" of Saifura Hussaini Ahmed Khorsa, who was abducted in Rann, in the far north of Borno state, on March 1. "We are devastated by the murder of our colleague Saifura," said Eloi Fillion, the head of the International Committee of the Red Cross (ICRC) delegation in Abuja. No details were given about the circumstances of her death but the ICRC called on the Islamists to release another midwife and nurse still being held. "There is no ideology or religious law that could justify doing any harm to them," said Fillion. The UN's humanitarian coordinator in Nigeria, Edward Kallon, said "the killing of Ms. Hussaini, a young, dedicated and passionate midwife and humanitarian, is a cowardly, heinous and despicable act".* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook"This incident demonstrates the severe challenges that Nigeria continues to face," he added. Humanitarian work was suspended in March after Boko Haram attacked Rann, killing three aid workers and eight Nigerian soldiers. The announcements by the ICRC and the UN are the first public news about the women since they were kidnapped. Rann is a remote town on the border with Cameroon where more than 60 000 people who have fled from Boko Haram jihadists depend on emergency food aid and medical care to survive. The Islamist group has intensified attacks in recent months, with the violence spilling over into neighbouring Chad, Niger and Cameroon.The jihadists have increasingly turned to kidnapping for ransom as a way to finance their operations and win back key commanders in prisoner swaps with the Nigerian government.