In a constituency where there is only one candidate, the law requires that the candidate must receive the support of at least 20 per cent of total eligible voters to win an MP seat.

"So far, there are 38 constituencies in 15 provinces where the single candidate has failed to get the minimum 20 per cent support," EC secretary-general Ekachai Warunpra-pha said.

He said the EC would today discuss when the by-elections should be called in these constituencies as well as in Nonthaburi's constituency 3, where there was no candidate on April 2.

Initially, Pimpha Chanprasong of the Thai Rak Thai Party planned to run for the MP seat in Nonthaburi's Constituency 3 - but was disqualified because she did not vote in the previous election.

However, Ekachai yesterday said the EC would allow Pimpha to run in the upcoming by-election because she had cast her ballot on Sunday.

He shrugged off criticism that it was too soon to return her right to contest the by-election.

Ekachai also disclosed that the EC was seeking to overturn the Administrative Court's order that the EC cannot provide only a rubber stamp to mark a ballot at the polling stations.

"We have already lodged an appeal," he said.

Ekachai insisted that eligible voters could keep their political choice confidential when they cast their vote even though they were required to face election officials when doing so.

"Other countries such as Japan and Australia have arranged it this way," he added.

Ekachai said the EC was ready to prove that ballots could be cast secretly when the polling booths were arranged this way.

"We will prove that before a new election," he said.