The trial of ex-Burundian president Domitien Ndayizeye and six others accused of plotting a coup, began in Bujumbura Friday, but was adjourned after defense lawyers asked two of the three judges to step down because of possible bias.
Defense attorneys point out one of the judges is married to the nation's justice minister.
The seven suspects have been detained since August, when police said they had evidence of a coup plot against the country's leadership.
In a related development, several radio stations have declared a news blackout day to protest the arrest this week of two journalists who reported on the case. The stations are playing music but omitting newscasts.
Burundi's government has come under increasing scrutiny over its record of democracy and freedom of expression, following a spate of arrests of activists and journalists since May.
The country is struggling to emerge from a long civil war that killed more than 300,000 people.
Some information for this report was provided by AFP and Reuters.