Ms Muthoki Mumo and Angela Quintal, who were on a work assignment in Tanzania were arrested and detailed by Tanzanian authorities on Wednesday.
Angela Quintal, CPJ's Africa programme coordinator and Ms Muthoki Mumo, CPJ's sub-Saharan Africa representative, who were on a work assignment in Tanzania were arrested and detailed by Tanzanian authorities on Wednesday and taken to an unknown location under unclear circumstances.
Ms Quintal, a former Mail & Guardian editor tweeted that officers, who identified themselves as Tanzanian immigration officers, detained her and Mumo in their hotel room in Dar es Salaam, Tanzania.
CPJ stated that the officials went ahead and ransacked the pair's belongings and would not return their passports when asked before escorting them to an unknown location.
However, after intense criticism locally and abroad with CPJ calling for their immediate release, Tanzanian authorities released them on Thursday.
It is not yet clear if they were charged with anything.
South Africa's Department of International Relations and Cooperation (DIRCO) later tweeted that the two journalists were back in their hotel.
"South Africa's High Commissioner Mr Thami Mseleku is meeting with them to discuss last night’s [Wednesday] events. He will then engage Tanzanian authorities. DIRCO spokesperson, Mr Ndivhuwo Mabaya, spoke to Ms Quintal this morning," the SA Foreign ministry tweeted on Thursday.
Both Ms Quintal and Ms Mumo's Twitter handles have been suspended and yet to be restored.
The international body has also called on President John Magufuli’s administration to drop allegations of illegal assembly against a local journalist.
Sitta Tumma, a reporter with privately owned Tanzania Daima newspaper, was arrested on August 8th and detained overnight while covering an opposition’s campaign ahead of a local by-election in Tarime District, 750km north of the administrative capital Dodoma.
"Tanzanian authorities should investigate those who arrested and assaulted journalist Sitta Tumma, instead of intimidating him with a bogus investigation into his reporting at a political event," said CPJ's sub-Saharan Africa representative, Muthoki Mumo.
Even though Mr. Tumma repeatedly identified himself as a journalist, he said he was assaulted during detention and accused of unlawful assembly.
Mr Tumma was released on August 9 on bond but police told him he may be required at any time to assist in investigations, according to his lawyer Ernest Mhagama.
Tanzania has in recent times come under severe criticism for cracking down on dissent and closing down on freedom of speech space.
European Union is considering slapping sanctions against Tanzania and on Saturday recalled its head of delegation in the country, Mr Roeland van de Geer, "to discuss the situation in Tanzania".