Uganda's main opposition leader Kizza Besigye has pleaded not guilty to charges of treason.

Twenty two co-defendants also entered pleas of innocence during a hearing in Uganda's High Court Tuesday.

Besigye's supporters say the treason charge is one of several the government made up to keep him from making an effective challenge to President Yoweri Museveni in recent elections.

Museveni won the February election but Besigye's party has asked the Ugandan Supreme Court to nullify the results.

The High Court dropped rape charges against Besigye last month, and President Museveni said Besigye would not be tried by a military court that had charged him with terrorism and illegal arms possession.

The treason trial proceedings have been adjourned until Wednesday because the court did not have a translator for the first prosecution witness, a woman who speaks the Acholi language.

Some information for this report was provided by AP and Reuters.