Uganda’s main opposition presidential candidate Robert Kyagulanyi, popularly Bobi Wine says his life is being threatened following Thursday’s election.
The singer-turned-politician told the BBC that he rejected the results “with the contempt they deserve”.
He alleged there had been a lot of irregularities but Mr Museveni called it Uganda’s fairest ever vote.
Campaigning had been marred by violence in which dozens of people died.
Just ahead of voting day the government shut down the internet, a move condemned by election monitors.
They said confidence in the count had been damaged by the days-long cut. A government minister told the BBC on Saturday evening that the internet service would be restored “very soon”.
Bobi Wine said he was not being allowed to leave his house which was surrounded by security forces.
“Nobody is allowed to leave or come into our house. Also, all journalists – local and international – have been blocked from accessing me here at home,” he said.
Addressing what his party, National Unity Platform, might do now, he told the BBC that “all options are now on the table including but not limited to peaceful protest” but he stressed that he was not calling for violent insurrection.
The opposition candidate earlier said: “I will be happy to share the videos of all the fraud and irregularities as soon as the internet is restored.”