PHOTOS: Aung San Suu Kyi 'wins' in Myanmar by-polls

Myanmar's pro-democracy leader Nobel laureate Aung San Suu Kyi won a seat in the country's lower house of parliament on Sunday after defeating her two rival candidates in a by-election in her constituency, the main opposition party said.

Her National League for Democracy party announced at its headquarters that Suu Kyi had won in Kawhmu, south of the commercial capital Yangon, Reuters reported.

"Daw Aung San Suu Kyi has won. The NLD candidate has taken the Kawhmu constituency," an NLD official announced to cheers from hundreds of supporters, referring to Suu Kyi by her honorific title.

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Suu Kyi, who has spent a total of 15 years in detention since 1989, was contesting an election for the first time following her party's decision to end its boycott of a political system dominated by serving or retired military.    

The by-elections were being held to fill 45 vacant legislative seats. Myanmar's Election Commission has yet to verify any by-election results.

The vote is a key test of promised political reforms, though the military-backed ruling party remains dominant.

During the campaign, foreign journalists and international observers were given the widest access for years.

The European Union hinted that it could ease some sanctions if the vote went smoothly, BBC reported.