Ugandan authorities Monday arrested a top opposition politician and presidential hopeful as he was leaving a meeting near the capital, Kampala and reportedly charged him with treason.

Violence erupted as crowds surrounded the convoy of Kizza Besigye as he and members of his Forum for Democratic Change party were being escorted to the central police station in Kampala.

A member of Mr. Besigye's entourage who was traveling in his car, Beatrice Hamjuni-Smith, describes the scene to VOA.

"There's so many people in the streets, and shooting," she said. "They shoot them with tear gas and then they run away and come back. It's a mess, and, oh my God, it's a complete mess."

Ms. Hamjuni-Smith tells VOA riot police and other authorities surrounded the convoy and took them to the central police station, where she says government troops and police waited to take Mr. Besigye into custody.

She says the authorities have given them no indication as to why Mr. Besigye was arrested.

According to eyewitness reports, crowds in Kampala's streets burned cars, threw stones, and looted shops.

An army spokesman tells VOA it was the police, and not government troops, that arrested Mr. Besigye.

Reuters news service reports the director of prosecutions charged Mr. Besigye with treason, accusing him of trying to topple the government under the cover of a Ugandan rebel group in the Democratic Republic of Congo called the People's Redemption Army.

Mr. Besigye, who leads the political party Forum for Democratic Change, was a presidential candidate who ran against President Yoweri Museveni in the 2001 elections. He subsequently went into exile in South Africa following threats on his life.

The opposition official returned to Uganda on October 26th and is his party's presidential candidate in Uganda's elections, to be held next March.

Mr. Besigye has accused the Ugandan government of being a dictatorship and detaining political prisoners.

Ms. Hamjuni-Smith says Monday's arrest is political.

"I don't believe there are any specific charges. They are trying to get rid of him [Besigye] because of the reception he received and because of his political work," she noted.

Political parties in Uganda had been severely restricted in the past. It was only in July of this year that rules were relaxed following a referendum that allowed multi-party politics to be restored.

Several months ago, parliament had also abolished the two-term limit for president, leading many to speculate that Mr. Museveni intends to run again in next year's elections.