Media watchdog Reporters Without Borders on Thursday accused Shiite Huthi rebels who have taken near-total control of the Yemeni capital of harassing journalists.
The rebels went on the offensive earlier this month and spilled into Sanaa from their stronghold in the north.
On Sunday they agreed to a ceasefire after a week of deadly battles with army-backed Sunni militias that killed 270 people, but since then they have been in control of key Sanaa offices and institutions.
"A climate of terror has reigned in Sanaa ever since the rebels launched their offensive on 18 September, and the fighting with government forces is intensifying despite the ceasefire," said the rights group, known under its French acronym RSF.
The group expressed concern that the "Huthi rebels are deliberately targeting journalists and news media in the capital because of their work" and urged them "to respect the 21 September ceasefire and stop harassing media and media personnel".
RSF said rebels were still in control of "some official buildings, including the state radio and television" and had raided the homes of journalists, ransacked others and arrested reporters.
"Concerned for their safety, many journalists have gone into hiding and are censoring themselves or adapting their reports for fear of reprisals," said RSF.
The watchdog noted that the rebels had "refused to sign an appendix about the disarming of militias in the capital" when they inked Sunday's ceasefire agreement.
"This crisis, with its attacks on media and journalists, is not only jeopardising Yemen's political transition but is also a source of deep concern for the future of fundamental freedoms, including freedom of information," RSF said.