At least two people have died in riots in Uganda's capital over the treatment of opposition leader Kizza Besigye.
Security forces fired live ammunition, rubber bullets and tear gas to disperse protesters burning tyres.
Mr Besigye sought medical treatment after being tear-gassed in his car and bundled roughly into a truck when he was arrested on Thursday.
It was his fourth detention this month for his participation in a "walk-to-work" protest over high prices.
President Yoweri Museveni has said the walking campaign over the rise in the cost of living is illegal.
After his arrest Dr Besigye was charged with inciting violence but was released on medical grounds until 2 May.
The BBC's Joshua Mmali in the capital, Kampala, says Dr Besigye was taken to hospital from the court because he had been temporarily blinded.
On Friday evening, he was allowed by the authorities to fly to neighbouring Kenya to seek medical treatment.
Our reporter says footage of the arrest was broadcast on Ugandan television and the video-sharing website YouTube.
It showed plain-clothed policemen beating up Dr Besigye's supporters, smashing the window of his car and dousing the inside with pepper spray and tear gas before manhandling him into a vehicle and driving off. BBC NEWS
