By Georgina Prodhan and Laura Gardner Cuesta

LONDON (Reuters) - Uganda's main opposition figure hopes the state does decide to bring him to trial for treason after he was arrested nearly four months ago, as it would give him a platform to challenge February's presidential election result, he said on Friday.

Kizza Besigye, who came second in the Feb. 18 election, says he won the poll and that his victory was stolen by President Yoweri Museveni, who the electoral body said was the winner.

Besigye was arrested in early May after a video surfaced on social media depicting him taking the oath of office for president. He was charged with treason and held in detention until he was released on bail on July 12.

Besigye told Reuters he did not expect prosecutors to withdraw the case but nor did he expect it to come to court, leaving him in limbo.

"I want the court (case) to come up and we argue who won and who should have been sworn in," he said after speaking at an event at Chatham House, a think tank in London.

Independent monitors said Uganda's elections were marred by multiple flaws including a lack of transparency and integrity by the poll body, voter bribery and interference by security personnel.

In recent months local newspapers have reported on behind-the-scenes efforts to get the opposition and Museveni, who has ruled the country for 30 years, to engage in talks.

Besigye said such efforts to secure peace with the opposition were only aimed at securing his rule and foreign investments in Uganda.

"He needs ... some kind of at least appearance ... that there is some kind of consensus-building process going on," he said. "Because of the high political risk nobody's willing to go and invest in Uganda in the middle of teargas."

Opposition activists, mostly from Besigye's Forum for Democratic Change (FDC) party, held several protests in the post-poll period to denounce Museveni's victory, clashing with police who dispersed them with teargas, beatings and arrests.

Government spokesman Ofwono Opondo played down Besigye's concerns.

"It is him (Besigye) who tried to foul the political environment but he was promptly dealt with. There's total tranquillity throughout Uganda and we see a lot of investors from the region and the world expressing interest in Uganda," he said.

(Additional reporting and writing by Elias Biryabarema in Kampala; Editing by George Obulutsa and Alison Williams)