Ten aid workers who were abducted in South Sudan last week have been released, the International Committee of the Red Cross (ICRC) said on Monday."We are pleased that these 10 aid workers will now be able to return to their families," said Francois Stamm, ICRC head in South Sudan.The ICRC is commonly involved in mediating the release of captives and hostages.The United Nations in South Sudan said last week that an aid convoy had gone missing in the southwest of the war-torn country, close to the town of Yei, adding it was the second time aid workers had been abducted by an armed group this month.Aid workers have frequently been targeted during South Sudan's four-year-long civil war, with 100 killed since the outbreak of fighting in December 2013, according to the UN.The conflict has killed tens of thousands, forced millions from their homes and pushed millions more to the brink of starvation.The UN Office for the Coordination of Humanitarian Affairs (OCHA) said the 10 missing aid workers were all South Sudanese nationals from various UN agencies and charities.In a statement on Monday, OCHA blamed "an armed opposition group" for the abduction."I am deeply concerned by the insecurity faced by aid workers in South Sudan, who are risking their lives to save others," said Alain Noudehou, the UN's humanitarian chief in South Sudan.Colonel Lam Paul Gabriel, spokesperson for the opposition SPLA-IO, admitted holding the aid workers saying they had been held for entering an area "without any clearance".ICRC said the 10 abductees had been flown back to the capital Juba after their release on Monday."While we are relieved these 10 humanitarians have been released, we want to remind all parties to the conflict that aid workers are never a target," said Stamm.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.