Up to one million Thais were disenfranchised ahead of the kingdom's crucial recent election because of outdated lists of voters, an international monitoring group said Tuesday.
The Asian Network for Free Elections (ANFREL), which deployed observers nationwide for the polls, said the process was "peaceful and orderly" but raised "significant concerns" about the advance voting day held on June 26.
The opposition party linked to ousted ex-premier Thaksin Shinawatra won a majority of seats in the July 3 poll, which passed "without any major incident which would call into question the election's results," ANFREL said.
But the group said the use of a 2007 list of advance voters for this year's poll deprived 500,000 to one million people of the right to vote, with the election commission not properly informing voters of the need to re-register.
"To date, this issue is the most substantial problem encountered regarding election administration," said an ANFREL statement. About 47 million people were eligible to vote in the Thai ballot.
ANFREL added that "vote-buying and the detrimental effect of money politics" were still long-term challenges for Thailand, and the group flagged reports of intimidation and isolated cases of violence during the campaign.
Damaso Magbual, chairman of ANFREL, said the military had generally acted "professionally and neutrally" during the election, with some exceptions such as soldiers bringing weapons into polling booths when they cast their votes.
Four Thai soldiers were arrested in the northeast for allegedly intimidating opposition activists last week, police said, amid widespread concerns that the powerful army would meddle in the political system around the election.
After ousting Thaksin with a coup in 2006, the military has said it will accepted the result of the vote, which will see his sister Yingluck Shinawatra become Thailand's first female premier at the head of his Puea Thai party.
"I think (the) military will think twice before they do anything wrong, considering what is happening in the Middle East right now," Magbual said.