South Sudan has arrested at least 22 officials linked to the country's vice president since violent clashes broke out in the northeast last month, threatening the country's fragile peace, Human Rights Watch said on Thursday.
A fragile power-sharing agreement between President Salva Kiir and First Vice President Riek Machar has been put in peril by fighting between their allied forces in the country's Upper Nile State.
HRW said 22 political and military figures linked to Machar's party have been detained, according to the vice president's spokesman, with many of them held incommunicado.
"The lack of transparency and legitimate concerns about the legality of the arrests and detention of opposition leaders and others fuel instability in an already fragile security context," said Nyagoah Tut Pur, South Sudan researcher for HRW.
"Authorities should immediately reveal the fate and whereabouts of detainees," Pur added.
Among those arrested in recent days are Petroleum Minister Puot Kang Chol and deputy army chief General Gabriel Duop Lam.
HRW said Lam and five of his bodyguards were arrested in a way that constitutes an enforced disappearance, and their whereabouts remained unknown.
It said the petroleum minister was taken along with friends, family members, and bodyguards by the National Security Service, which "operates with limited legal and judicial oversight and de facto impunity" and was guilty of "torture and ill-treatment of detainees".
The government has not commented on the arrests.
But Information Minister Michael Makuei Lueth said last week: "If anybody is arrested, it is for a reason."
HRW called on the international community, including the United Nations and the African Union, to press the South Sudanese authorities to uphold human rights.
"South Sudanese authorities should cease arbitrary detention of opposition members and other actions that amount to harassment and not use the security institutions as a tool of oppression," Pur said.