The advance votes are for those who cannot get to the polling stations on election day on Wednesday.

About 1.64 million people voted in advance at the central polling stations of their respective constituencies, and some 77,400 cast ballots outside their constituencies.

Among the absentee voters, 105,563 were Bangkok residents.

Of 151,900 absentee votes cast in the central region, Suphan Buri had the highest turnout with about 27,500 ballots.

In the North, Nakhon Sawan ranked first in voter turnout with 40,700. About 379,500 absentee ballots were cast in the region.

In the South, Nakhon Si Thammarat had 34,800 absentee ballots. The region recorded 159,900 absentee voters.

The Northeast reported 608,400 absentee votes with Nakhon Ratchasima registering the highest turnout of around 76,000 votes.

With the second round of voting for the general election due next Sunday, radio talk-show host Chalee Nopawong na Ayutthaya said he was spearheading a local campaign to urge Songkhla residents to tick the "no-vote" box.

Chalee said the abstention ballots in the repeat vote would reaffirm the people's disapproval of the election.

"The government should heed public sentiment rather than push through an election outcome that fails to reflect the people's choice," he said.

About 17 Thai Rak Thai Party candidates will again run unopposed in the South after failing to muster 20 per cent of eligible votes in the April 2 ballot.