Opposition MP flew out of Uganda for medical treatment for alleged torture amid fresh protests in Kampala.

Robert Kyagulanyi, a Ugandan pop star-turned-opposition politician, has arrived in the United States for medical treatment following alleged torture in detention, a day after he was denied boarding.

Kyagulanyi, whose stage name is Bobi Wine, said in a post on Twitter on Saturday that he will be “receiving specialised treatment following the brutal torture at the hands of SFC soldiers”.

He added: “We thank the world for standing with us. I will tell you what exactly happened to me since 13th August and what is next.”

Safely arrived in the US where I'll be receiving specialised treatment following the brutal torture at the hands of SFC soldiers. We thank the world for standing with us. I will soon tell you what exactly happened to me since 13th August and what is next. #peoplepower Power pic.twitter.com/0IcA3wUAQd — BOBI WINE (@HEBobiwine) September 1, 2018

On Friday, the 36-year-old’s lawyer in Uganda, Nicholas Opiyo, posted a video on Twitter which showed his client as he was taken to a departure gate at Entebbe International Airport on a wheelchair, saluting and thanking supporters along the way.

Robert Amsterdam, Kyagulanyi’s international lawyer, told Reuters news agency that the politician was headed to the eastern US city of Boston and was also expected to travel to Washington, DC, during his stay.

Kyagulanyi, who has emerged as a formidable political threat to President Yoweri Museveni, was arrested and charged with treason in August after protesters stoned the Ugandan leader’s car during a by-election campaign.

The legislator’s arrest sparked violent protests with his supporters saying he was badly beaten and tortured while in army custody, during and after his detention in the northwestern town of Arua on August 13, and required medical treatment abroad.

Kyagulanyi was released on bail on Monday without any travel restrictions. But he was arrested again by police on Thursday evening at the airport, outside the capital, Kampala, his lawyers said.

Amsterdam, his lawyer, told Al Jazeera on Friday that Kyagulanyi said he had been tortured again while being transported from the airport to a hospital in Kampala.

“Burn marks are showing up on his body,” Amsterdam said. “We want to get him to an independent clinic for assessment.”

Police spokesperson Emilian Kayima called the allegations “fake news”.

In a statement late on Friday, Kayima said that the director of public prosecutions instructed the police to investigate allegations of torture on Kyagulanyi, a move that required that he be examined by government medical experts.

“Before this medical examination was done, the Uganda Police Force learned of his departure yesterday, August 30,” said Kayima in the statement. “As a result, Hon Kyagulanyi was halted from departure.”

The re-arrest of Kyagulanyi triggered fresh protests in Kampala on Friday.

Soldiers were sent to Kampala’s streets to put down protests by Bobi Wine’s supporters [File: AP]

People demonstrated in different parts of the city, burning tyres and piling rocks and other barricades in the middle of the roads. Police said the protests were limited and contained.

Kyagulanyi is a musician who entered politics after winning a parliamentary by-election last year. He has emerged as a formidable threat to Museveni’s 32-year rule, winning popular support through his music and strong criticism of the government.

In July, the Constitution was amended to remove the presidential age limit of 75 years, meaning Museveni, 74, can run again for president in 2021.