Two of four journalists who were detained in January after a video appearing to show South Sudan president wetting his trousers at a public function have been released went viral.
The Union of Journalists of South Sudan (UJOSS) said in a statement that it welcomed the release of Victor Ladu and Mustapha Osman.
In December last year, a video shared on social media appeared to show Mr Kiir urinating on himself as the national anthem played at a function.
Six staff from the state broadcaster were later arrested, but two remain in detention.
"[We] urge the government to release Garang John and Jacob Benjamin or if they have a case to answer, they should be produced in a court of law," UJOSS statement said.
The arrests had been condemned by rights groups including The Committee to Protect Journalists (CPJ).
The arrests match "a pattern of security personnel resorting to arbitrary detention whenever officials deem coverage unfavourable", said CPJ's sub-Saharan Africa representative, Muthoki Mumo said at the time.
