The Committee to Protect Journalists says Ethiopia's government has charged nine journalists with terrorism and inciting violence.
The watchdog group said the journalists include six bloggers from Zone 9, an independent collective that publishes critical news and commentary. They were arrested in April.
The group urged Ethiopia's government to release all the journalists, saying they were in detention simply for doing their jobs.
Ethiopia's government has faced persistent criticism from watchdog groups over its alleged harassment of independent journalists.
Critics say the government uses sweeping anti-terrorism laws to intimidate reporters and suppress political dissent.
More than a dozen critical journalists have been jailed since 2009, according to the Committee to Protect Journalists.