The four, all members of the opposition Oromo Federalist Congress (OFC), have been in pre-trial custody since their arrest in late 2015 when a wave of anti-government protests broke out.
Bekele, the deputy OFC chairman, and the three other party officials broke into song on Thursday after the judges ruled against his request to summon Prime Minister Hailemariam Desalegn and other high-ranking government officials as defence witnesses, their attorney Ameha Mekonnen said.
“They were furious, they were saying things that really undermined the judiciary,” Ameha said.
“After they made many complaints and … then they continued to sing their songs.”
Three other prisoners in the courtroom for an unrelated case were also sentenced to three months in jail for clapping to the song, which criticised government land seizures.
Though the OFC officials have been imprisoned for more than two years, that jail time won’t count for the six month term for contempt of court, Ameha said.
Bekele has become a cause celebre for protesters from the country’s largest ethnic group, the Oromos, who started rallying more than two years ago over government policies they feared would deprive them of their land.
The protests left hundreds dead and prompted parliament to declare a 10-month state of emergency in 2016.
Originally charged under the country’s terrorism law, the court last July downgraded Bekele’s charges to “provocation” under Ethiopia’s criminal code.
Speculation that Bekele would be released began earlier this month after Hailemariam told reporters that the government would free some jailed politicians “in order to improve the national consensus and widen the democratic platform.”
But the prime minister provided no details, and none of the many politicians jailed in Ethiopia have been freed since the announcement.