The opposition leader says that young Ugandans must continue their defiance of the Museveni regime.
Eight top Ugandan police chiefs are accused of brutalizing Kizza Besigye's supporters.
The Ugandan president also recently promoted his son to one of the military's highest ranks.
Besigye is being held in Uganda's only maximum security prison.
Muhoozi Kainerugaba trained at Sandhurst and has made a quick ascent through the army's ranks.
Kizza Besigye has been under house arrest since February 18 elections.
The Forum for Democratic Change has been demonstrating against Museveni's controversial victory.
The police have denied they were involved and accused Mbabazi of "dirty tricks."
President Yoweri Museveni was re-elected in a controversial presidential election in February.
President Yoweri Museveni won Thursday's controversial elections with 61 percent of the vote.
President Yoweri Museveni cements his 30-year grip on power in the East African nation.
Despite the blackout, #UgandaDecides is still trending.
President Museveni said anyone trying to stir up violence ahead of the polls would be dealt with harshly.
Most Ugandans have never known a president other than Yoweri Museveni.
Besigye, Uganda's main opposition presidential candidate, was briefly detained on Monday.
Besigye is the main challenger to Yoweri Museveni in Thursday's elections.
Museveni is seeking re-election on February 18 after 30 years in power.
David Sejusa, a prominent critic of the Ugandan president, has been charged with military offenses.
Uganda's former prime minister has ultimately failed to convince voters that the time for change is now.
The Ugandan president spent 12 times more than his two closest opponents combined in November and December.
Museveni is standing against his former doctor and a former prime minister in February's elections.