Kampala - Two South Sudanese men affiliated with the country's opposition have been detained by Kenyan authorities and are at risk of being deported back to Juba, according to their lawyer.Eddy Orinda told The Associated Press that Dong Samuel Luak and Aggrey Esbon Idri "are being held by police pending deportation" and don't know why they are detained.Luak is a prominent lawyer and opposition figure who has spoken out against human rights abuses. Idri is national chairman of the opposition SPLM-IO movement under rebel leader Riek Machar, according to party spokesperson Mabior Garang."Dong Samuel Luak is at serious risk of arbitrary detention, torture and other abuses if returned to South Sudan," said Leslie Lefkow, deputy Africa director at Human Rights Watch.Luak is a refugee, Lefkow said. Kenyan law and African Union agreements prohibit the return of refugees if their lives are at risk, Lefkow said.A Kenyan official confirmed the two men were in custody prior to being either deported or released. The official spoke on condition of anonymity because the official feared reprisals.Kenya's government has thrown its weight behind the government of South Sudan President Salva Kiir in recent months. In November, Kenya deported top opposition spokesman James Gatdet Dak to Juba, where he has been in detention. He also was a refugee.Kenya also withdrew around 1 000 peacekeepers from the UN mission in South Sudan after the force's Kenyan commander was fired over the mission's failure to protect civilians.South Sudan's civil war began in late 2013, and a peace deal signed in 2015 has failed to stop the fighting. Tens of thousands have died and more than 3 million have been displaced, according to the UN.