Two politicians who had been rising stars in Ethiopia's ethnic Oromo opposition movement have pleaded "not guilty” to terrorism charges in Addis Ababa on Monday.

Bekele Gerba and Olbana Lelisa appeared in federal court to hear charges accusing them of conspiring to overthrow Ethiopia's government by force. They also stand accused of being recruiters for the Oromo Liberation Front, an outlawed separatist group.

Bekele and Olbana had been considered among the brightest of the young generation of politicians being groomed to take over following the 2010 electoral disaster, when the opposition was virtually shut out of parliament. Bekele had been named deputy chairman and external relations chief for the Oromo Federal Democratic Movement (OFDM), and Olbana held a similar post in the Oromo People's Congress.

Bekele, an English instructor at Addis Ababa University, was also on the executive board of the main opposition bloc Medrek.

The men were arrested last August after meeting with a visiting delegation from the Amnesty International rights group, which was later expelled from the country.

Along with seven co-defendants, Bekele and Olbana had also assisted a BBC news crew that been investigating allegations that Ethiopia used billions of dollars in development aid as a tool for political repression. The government strongly denied the report, calling it irresponsible.

In court Monday, Bekele tried to argue that he had been working for peaceful change on behalf of what he called "downtrodden Oromos," who comprise Ethiopia's largest ethnic group. Chief Judge Endeshaw Adane cut him short, saying the hearing was only for entering a plea.

Dr. Mogga Frissa, who heads both OFDM and the Medrek opposition bloc, says the court's handling of the case and the long delay in bringing defendants to trial constitutes unfair treatment of Oromos.

"(The) Oromo community is disappointed with this," he says. "They are oppressed, they have no right of talking, they have no right of expressing themselves. Every Oromo. They have kept them for almost [four] months and only today they have asked them if they are guilty or not, so this shows the Oromos are oppressed."

The trial is scheduled to continue Tuesday at the same high-court complex where a verdict is due in the case of two journalists also charged with terrorism. Reeyot Alemu, a columnist with the weekly paper Fitih [Justice], and Woubshet Taye, deputy editor of the now defunct Awramba Times, are charged with plotting to sabotage telephone and electricity lines.

In a third terrorism trial slated to resume later in this week, opposition politician Andualem Aragie and internet blogger and political analyst Eskinder Nega are among 30 defendants charged with conspiring to overthrow Prime Minister Meles Zenawi's government by violent means. While Eskider and Andualem will be in the courtroom, most of the defendants are in exile and being tried in absentia.

All those charged in the three cases have been outspoken critics of Meles and his ruling Ethiopian People's Revolutionary Democratic Front, which has been in power for more than 20 years. Human rights and press freedom groups have accused the EPRDF of using the terrorism law to silence dissent. The government staunchly denies the charges.

Two Swedish journalists were convicted on terrorism-related charges in the same court last month and sentenced to 11 years in prison. The pair had been arrested in the company of an outlawed rebel group in Ethiopia's restive Ogaden region.