Prominent Ugandan opposition figure Kizza Besigye has appeared before a military court in the capital, Kampala, where he has denied charges that include the illegal possession of firearms and negotiating to buy arms abroad.

His appearance comes after his wife said he was kidnapped in neighbouring Kenya last Saturday and sent back home where was being held in a military jail.

In a post on X, Winnie Byanyima wrote that her 68-year-old husband had been seized in Kenya's capital, Nairobi, during a book launch event - and she demanded the Ugandan government free him.

Besigye was told during the military court hearing, held amid heavy security, that he would remain in custody until 2 December.

Besigye - who has contested and lost four presidential elections against President Yoweri Museveni - appeared along with his co-accused, opposition politician Obedi Lutale, who also denied the charges.

The four counts they face include being found with two pistols and ammunition in a hotel in the Kenyan capital and negotiating for arms with foreigners in the Swiss city of Geneva, the Greek capital, Athens, and Nairobi.

On his arrival at the Makindye military court - after being incommunicado for days, Besigye waved to the gathered journalists and senior members of his Forum for Democratic Change (FDC) party.

As the hearing got underway, Besigye objected to being tried in a court-martial, saying that if there were any charges against him, he should be tried in a civilian court.

But he was overruled and the hearing continued.

Earlier, his wife, a respected human rights advocate and executive director of UNAids - the joint UN programme set up to eradicate the disease, had said in her tweet: "He is not a soldier. Why is he being held in a military jail?"

Besigye used to be Museveni's personal doctor but went on to become an opposition leader and has referred to the leader of the East African country, who has been in power since 1986, as a "dictator".

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

Besigye’s alleged kidnapping has raised concerns in Kenya, where rights groups have voiced alarm recently after a spate of forced deportations from the country, once regarded as a safe haven for refugees from across the region, and further afield.

Kenya's state-funded human rights body, the KNHRC, has expressed concern over Besigye’s case.

The Pan-African Opposition Leaders Solidarity Network also said the matter was "deeply disturbing and of grave concern", adding that abductions by state security forces were not the legal way for cooperation between Uganda and Kenya.

Kampala Mayor Erias Lukwago, one of Besigye's close political allies, has demanded a response from the Kenyan government over the issue.

"The manner and circumstances surrounding his arrest are really disturbing to us... [it] is shrouded in mystery. The government of Kenya owes us an explanation," he said.

But Kenyan government spokesman Isaac Mwaura told the BBC he was not aware of any abduction and the top civil servant in the foreign affairs ministry, Korir Sing'oei, said he had not even been aware Besigye was in the country.

"Kizza Besigye visits Kenya many times, he is a leader who has friends, family here... [but] he didn't tell us that he was coming to Kenya as the foreign affairs ministry, or that he needed any facilitation. We understand him, we value him and we hope that his situation can be resolved by the neighbouring country," Sing'oei told the BBC.

Besigye has been less active in politics in the last couple of years and did not contest the 2021 election, telling his supporters in April that he had taken a political break.

But he announced he was returning to the political fray for the next two years to sort out the "chaos" in his party, which has split into two factions.

He said he wanted to retire at 70 and would "push hard" to help Ugandans in the little time he had.