KAMPALA, Uganda – Uganda’s opposition leader was remanded Wednesday to a maximum security prison in the capital after being charged with treason for organizing protests against the re-election of long-time President Yoweri Museveni.

Kizza Besigye briefly appeared in a magistrate’s court in Kampala to be charged before he was driven away under heavy guard to a jail on the shores of Lake Victoria.

Besigye was charged afresh after being transferred from Moroto, where had been detained after the treason charges were first read to him last week, said Solomon Muyita, a spokesman for the judiciary. Treason has a maximum penalty of death upon conviction. Besigye will return to court on June 1.

Besigye came second in presidential elections held in February, but rejected the official results as fraudulent and called for an international audit of the results, one of the reasons cited for charging him with treason.

The polls were marred by violence and delays in delivery of voting materials in areas seen as opposition strongholds, as well as a government shutdown of social media. Election observers cited many irregularities, with the European Union delegation saying the election commission lacked independence.

Uganda’s top court heard a petition against Museveni’s victory and ruled he was validly re-elected. Despite the court’s decision, Besigye has urged his supporters to wage a defiance campaign over the disputed polls as well as what he says is harassment by the security forces.

Besigye has been repeatedly arrested by the police, who sometimes detain him inside his own home.

Museveni, who took power by force in 1986, has been elected five times since 1996. All the elections have been marred by allegations of rigging.