"This was a country-wide problem," said Rubaramira Ruranga, head of electoral affairs for Kizza Besigye's coalition.

Besigye's staff had promised to announce their own set of results less than 24 hours after polls closed in the February 18 election, relying on a team of agents dispatched around the country to collect tallies from polling stations.

Several of those agents said Tuesday they were arrested by uniformed police shortly after arriving at their assigned station, and only released after the Electoral Commission declared Museveni the winner with 68 percent of the vote.

"They thought if they released us before announcing (the results) we could cause disorder in the country," said Ben Kanakulya, explaining his detention in the central Kyankwanzi district on Friday and subsequent release Monday.

"Some (of us) didn't last longer than 40 minutes," according to John Wassaja, describing his prompt arrest in the central Sembabule district after identifying himself as an opposition vote protector.

"They said, 'you have come from Kampala, and we only want agents who are local," he added.

Some of those present at Besigye's campaign headquarters Tuesday, said they observed some voting before being detained, and described election officials who permitted armed ruling party loyalists to vote repeatedly.

"A man comes. He shows his gun. That one is the password. They don't just give him one ballot. They give him what he likes," said Mathew, 24, who observed voting in the central Kibogo district and who requested his second name be withheld.

Shortly after Besigye's polling agents briefed the media about their experiences, several armed security officials arrived at his campaign headquarters, according to an AFP journalist.

Besigye left the premises without addressing journalists in person.

After securing re-election Sunday, Museveni is set to extend his rule to 30 years, one of the longest tenures in Africa.