The wife of Ugandan opposition figure Kizza Besigye says he has been kidnapped and is now being held in a military jail.

In a post on X, Winnie Byanyima wrote that her husband had been seized in Kenya's capital Nairobi last Saturday during a book launch event.

"I am now reliably informed that he is in a military jail in Kampala," she said, demanding that the government of Uganda release her husband.

BBC News has asked the Ugandan government for comment on the issue.

Besigye, 68, led the Forum for Democratic Change (FDC) political party, contesting and losing four presidential elections against incumbent Yoweri Museveni, who has been in power since 1986.

"We his family and his lawyers demand to see him," his wife wrote on X.

"He is not a soldier. Why is he being held in a military jail?"

Winnie Byanyima is a human rights advocate and executive director of Unaids, the joint UN programme which was set up to eradicate Aids.

Kizza Besigye used to be Museveni's personal doctor but he went on to become an opposition leader and has referred to leader of the east African country as a "dictator".

He has alleged that previous presidential elections were rigged - a claim denied by the government.

The opposition figure has been arrested on numerous occasions in the past.

On one occasion he was shot in the hand, on another he suffered eye injuries after being doused in pepper spray.

The authorities have accused him of provoking them, and he has been charged with inciting violence.