According to the Kenya Union of Journalists Executive Director Juma Kwayera who spoke to Kahawa Tungu, the communication devices for the two have been tampered with by the Tanzanian police.
The two, a former Nation journalist Muthoki Mumo and South Africa's Angela Quintal, were arrested while in their Dar es Salaam hotel room and detained at an unknown location.
"We believe that the detention of journalists is a direct and unsafe threat to media freedom and access to information". They were released on Thursday morning but are yet to get their passports back.
Quintal, the Africa program coordinator at the Committee to Protect Journalists, and Mumo, the organization's sub-Saharan Africa representative, were in Tanzania for a reporting mission.
Officers who identified themselves as working with the Tanzanian immigration authority detained Quintal and Mumo when they arrived at their hotel room.
"After approximately five hours, Quintal and Mumo were then returned to their Dar es Salaam hotel, at around 3am - but without their passports". The officials searched the pair's belongings and would not return their passports when asked.
The South African National Editors' Forum (Sanef) called on the government to find answers as to why Quintal and her Kenyan colleague were detained in Tanzania. "The United States remains committed to the values of democracy, rule of law, freedom of expression, and prosperity in Tanzania".
"We continue to engage with our Government of Tanzania counterparts on a wide range of issues, including those related to human rights", the State Department said in a statement.
They were detained by Tanzanian authorities on Wednesday night for reasons that remain unclear.