South African investigative journalist Micah Reddy, who was reported missing in Djibouti, is believed to have been detained by authorities.
The International Consortium of Investigative Journalists (ICIJ) says Reddy is believed to have been taken into custody after allegedly failing to obtain the required media accreditation.
Djiboutian journalist and ICIJ Africa Coordinator Mohamed Willo Ismael is also reportedly being held by authorities.
Concern was raised after Reddy's family, colleagues and media freedom organisations lost contact with him.
Reddy, who is based in Johannesburg, has previously worked for investigative journalism organisation amaBhungane and the Yemen Times.
Contact with Reddy and Ismael was lost in Djibouti City on Saturday, 19 September.
The ICIJ says it is still seeking information about the circumstances surrounding their reported detention.
The organisation has called for clarity on the journalists' whereabouts and their treatment while in custody.