Ugandan security forces have deployed heavily before the return of pop star and opposition figure Bobi Wine from the United States.
Lawyer Asuman Basalirwa says police have detained the singer's brother and at least two other people who were driving to the airport to welcome him home. Authorities say they will not permit any rallies related to his arrival.
Wine, whose real name is Kyagulanyi Ssentamu, is expected to arrive at Entebbe International Airport midday Thursday.
He had sought treatment in the US for injuries allegedly sustained during state torture, which Uganda's government denies.
The singer, who won a national assembly seat last year, faces treason charges over his alleged role in an incident last month in which the president's convoy was pelted with stones. He denies wrongdoing.