A group of Ethiopian bloggers and journalists held in jail for nearly three months have been charged with terrorism for having links to an outlawed group and for planning attacks, a judge said.

The seven members of the blogging collective Zone Nine and three journalists were arrested in April, prompting an outcry from rights groups who said the case was an assault on press freedom.

"They took training in how to make explosives and planned to train others," Judge Tareke Alemayehu told the court on Friday.

The judge said their work was a cover for "clandestine" activities and accused them of plotting "to destabilise the nation".

The group is accused of planning attacks in Ethiopia and working in collusion with the US-based opposition group Ginbot 7, labelled by Ethiopian authorities as a terrorist organisation.

Charges rejected

The Zone Nine website, proclaiming "we blog because we care!" features mostly social and political commentary, often critical of the government.

Nine of the accused smiled and waved to friends and family as they entered the packed courtroom. The tenth defendant is being charged in absentia.

The lawyer for eight of the suspects dismissed the charges.

"We don't believe that there is any credible substance," Amaha Mekonnen told AFP.

Rights groups have accused Ethiopia of using the anti-terrorism laws to silence dissent and jail critics.

Several journalists have been jailed under the law, including two Swedish journalists sentenced to 11 years in prison in 2012. They were pardoned after serving 15 months.

The dissident blogger Eskinder Nega is serving an 18-year sentence for having links with Ginbot 7, which calls for the violent overthrow of the ruling party.

The trial for the bloggers and journalists is expected to resume on August 4.