Uganda’s opposition leader Kizza Besigye was arrested Monday while he tried to leave his house after being placed under house arrest since Friday, the Associated Press (AP) reported. The latest detention is the fourth in eight days for Besigye and comes after he lost to long-time President Yoweri Museveni in the elections last week.

The AP report added that Besigye, who had alleged that the voting was rigged, had planned to visit the election commission’s headquarters in Kampala on Monday in an effort to get more details on the results of the election held Thursday. The commission had announced that Museveni won the election with over 60 percent of the votes while Besigye clocked 35 percent of the votes. Besigye has since denied the results from being valid and has been calling for an independent audit into the results, to be conducted by members from the international community.

Besigye also said, according to AP, that he may petition the Supreme Court and was trying to gather evidence for it. He had asked his supporters to “use the popular numbers that we have to make sure that the gunmen do not do what they are doing.”

He had said: “If the regime continues to restrict me, to detain me in my home ... I call upon all of you citizens to protest this,” adding: “At the very minimum let us also stop them from moving.”

Police spokesman Patrick Onyango said, according to Reuters: “Today, (Besigye) had mobilized a group of youth to storm the electoral commission. We had information that they had planned to cause violence in the city,” adding that he was not believed to have obtained consent for movement.

Ingrid Turinawe, a senior official with Besigye's Forum for Democratic Change party, said, according to Reuters, that he was arrested so he is unable to put together the evidence needed to challenge the election results. “They should leave him to be free because he has only 14 days to petition the court. He has to collect evidence,” she said.

According to the AP report, Besigye was thrown into a van by officials and was taken to an unknown location while a security agent in plain clothes used pepper spray on a journalist.

The European Union had said in its preliminary report, according to AP, that the election, which faced several delays and witnessed few incidences of violence, had an “intimidating atmosphere, which was mainly created by state actors.” The report also added, according to AP, that the election commission lacked independence and transparency. A Reuters report cited the U.S. Secretary of State John Kerry's concern over the harassment of opposition figures and the way social media sites stopped working intermittently during the polls.

Museveni, 71, denied the allegations against him and his administration Sunday and asked European leaders not to lecture him. “I told those Europeans ... I don't need lectures from anybody,” he said, according to Reuters. He also vowed to “use both soft and hard means to guard the peace in Uganda," AP reported.

Museveni gained control of Uganda by force in 1986 and got the country out of chaos after a guerilla war. Despite being a key ally to the U.S. on security matters, critics are concerned that he may rule for life. They have also accused him of using security forces to intimidate and clamp down on opposition.