Kizza Besigye was charged at a magistrate court without the presence of his lawyers, Justice Ministry spokesman Solomon Muita told dpa on Saturday.

Treason carries a possible death sentence in Uganda.

Besigye was subsequently arrested and flown to the remote town of Moroto, roughly 500 kilometres north-east of the capital, Kampala.

Museveni was sworn in for a new five-year term on Thursday.

The 71-year-old president, who has ruled the East African country since 1986, took 60 per cent of the vote in general elections held February 18.

The opposition says the elections were rigged.