Besigye is being held in Uganda’s only maximum security prison.
President Yoweri Museveni was re-elected in a controversial presidential election in February.
The international community responded in a variety of ways to Museveni's re-election.
President Yoweri Museveni won Thursday's controversial elections with 61 percent of the vote.
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 is the main challenger to Yoweri Museveni in Thursday's elections.
Amama Mbabazi has pledged to return Amin’s remains to Uganda if he is elected.
David Sejusa, a prominent critic of the Ugandan president, has been charged with military offenses.
Museveni is standing against his former doctor and a former prime minister in February’s elections.