The party linked to Thailand's ousted prime minister Thaksin Shinawatra has won a parliamentary majority in Sunday's general election, and his younger sister is poised to become the country's first female prime minister.

With nearly all the votes counted, the Pheu Thai party secured a clear majority of 264 seats out of 500, well ahead of Prime Minister Abhisit Vejjajiva's Democrats with about 160.

Mr. Abhisit conceded defeat Sunday and congratulated his opponent Yingluck Shinawatra.

The United States issued a statement congratulating Thailand for its voters' “robust participation” in the election.

Thailand has been deeply divided since the kingdom's military staged a bloodless coup that ousted Mr. Thaksin in 2006.

From exile in Dubai, the former prime minister hailed the outcome of the election. He has lived abroad to avoid a prison sentence on charges of corruption in Thailand. He says he is innocent and that the charges were politically motivated.

Mr. Thaksin's supporters formed the bulk of protesters dressed in red shirts that demonstrated in Bangkok last year, demanding the resignation of Mr. Abhisit's government. More than 90 people were killed in the clashes when the protests turned violent.