Dr Besigye had vowed to peacefully march to electoral commission to demand proof of poll outcome.
Museveni wins 60.8% of the vote while rival Kizza Besigye claims 35.4% of the vote.
Violence has erupted in Uganda's capital Kampala. Police responded tp protests with tear gas and bullets.
Free Uganda has accused President Museveni of plotting to 'fraudulently declare himself president'.
UPDATE: Leader Dr Kizza Besigye not 'escorted back to his home' but 'held at police station'
EXCLUSIVE: FDC party official tells IBTImes UK charges against Besigye were 'blanket of an excuse'.
The 30-year president promised there would be violence after voting in the 18 February elections.
EU election observer chief calls vote 'worrying' amid reports Kampala had yet to receive ballot boxes by 12pm
Aide admitted he has 'no idea where Besigye is'.
Fear of violence are running high as 15 million Ugandans head to presidential polls
Read President Yoweri Museveni's impromptu speech in full.
Growing reports of clashes between police and voters in some districts as polling stations close.
Communication commission claimed 'people were using social media and money services to bribe voters'.
Museveni aiming to secure 5th term amid reports of violence
EXCLUSIVE: African Union electoral observer tells IBTimes UK about widespread irregularities in run-up to poll
Tensions ignited after Ugandan opposition leader is detained by police claims life of protester
Ugandan opposition candidate Kizza Besigye detained by police on the way to Kampala rally
Violations since 1997 posed serious risks for Ugandan's ability to freely exercise their human rights.
Uganda's controversial former intelligence chief David Sejusa appears in court
Over 300 people have been killed in violence accompanying President Nkurunziza's controversial third term.
Activists hope Pope Francis will preach tolerance toward homosexuals and call for peaceful elections
Pope Francis will be making his first visit to Africa over five days