Uganda’s military have charged the main opposition leader, Kizza Besigye, with terrorism and illegal possession of firearms.
Last week, civilian prosecutors accused him of treason.
Mr Besigye has mounted the strongest challenge to President Yoweri Museveni’s 19-year rule.
But his defence lawyer said Mr Besigye refused to answer the terrorism charge, which carries the death penalty, because he says the accusations were fabricated.
Mr Besigye returned from exile last month. He denied past accusations from the government that he led the People’s Redemption Army and had links with separate rebels of the Lord’s Resistance Army.
Today, the Ugandan government banned the media from reporting on court cases, including that of Mr Besigye.
CHOGM wants answers
The arrest has cast doubts on President Museveni’s stated intention to comply with international pressure and introduce multi-party politics to the African country.
And Commonwealth leaders are concerned about perceived human rights violations in Uganda and will raise the issue in talks with the long-time President.
“I’d like to have a talk with President Museveni,” Commonwealth
Secretary-General Don McKinnon said.
The Commonwealth had pushed Uganda “very hard toward multiparty democracy,” Secretary- General McKinnon added.
President Museveni arrived yesterday in Malta for the Commonwealth’s biennial summit.
Uganda is due to host the next summit of the organisation’s 53 member states.
But the arrest of Mr Besigye has cast doubts on Uganda’s fitness to host the next meeting in 2007.