The rebels of South Sudan have released 18 Bangladeshi peacekeepers detained on the Nile river, but another 12 United Nations (UN) contractors captured alongs with them are still detained in the town of Kaka, in the country's state of Upper Nile.
The 20 peacekeepers were detained in Malakal on Monday, as they were carrying fuel for the UN mission, by around 100 heavily armed rebels affiliated with Sudan's People's Liberation Army (SPLA), UN spokesman Stephane Dujarric said earlier.
UN spokesman Stephane Dujarric demanded that the contractors be "released immediately, unharmed and unhurt," warning that the attacks against peacekeepers could be considered as a war crime.
The 18 Bangladeshi soldiers on Thursday were taken out of of Kaka by UN helicopter to Malakal.
The UN voiced concerns about the fate of the peacekeepers, calling on rebel leader Riek Machar to "uphold his commitment to the United Nations that all be returned safely," said Dujarric.
Machar and the UN's peacekeeping chief Herve Ladsous talked over the phone with Machar on Thursday to personally appeal for the release of the peacekeepers.
The conflict in South Sudan, which emerged after it gained independence from Sudan in 2011, has killed over 10,000 people and displaced more than 2.2 million.
The country descended into chaos in December 2013 when a political row between Kiir and his deputy Riek Machar spiralled into armed conflict that reopened ethnic faultlines.
Since then, more than 12,500 peacekeepers have been deployed in the country.