A Ugandan court on Friday denied bail to leading opposition figure Kizza Besigye and another defendant, with the judge citing the heavy charges they face and the ongoing investigation.

Besigye, 68, is a leading opponent of President Yoweri Museveni - in power for nearly 40 years - and was abducted from Kenya in November to face treason charges at home.

The United Nations and rights organisations have expressed growing concern about the suppression of Uganda's opposition in the run-up to presidential elections in 2026.

"Although all grounds for bail are met. The applications for bail are denied," High Court Judge Rosette Comfort Kania ruled Friday.

National security

"The investigations are ongoing and the applicants may fall prey to the temptation of interfering with those investigations" she said, adding the charges related to national security.

No new court date has been set.

Besigye and longtime party ally Obeid Lutale have been in prison for more than 140 days.

Defence lawyer Erias Lukwago questioned why bail was denied when the judge agreed the conditions had been met.

"We are going to fight on until the two get bail," he said.

Military court

The government initially sought to have them tried in a military court but later abandoned its bid and sent the case to a civilian tribunal.

Earlier this year, Besigye went on hunger strike while detained.

Once Museveni's trusted personal doctor, Besigye became a government target after joining the opposition 25 years ago and unsuccessfully running for president four times.