Late on Monday afternoon, the Election Commission (EC) said with 95% of the vote counted, its latest unofficial figures gave Pheu Thai 137 constituency seats and Palang Pracharat 79, followed by Bhumjaithai with 39, the Democrats with 33 and Future Forward with 30. 150 seats were yet to be decided.

Earlier, Secretary-general Ittiporn Boonprakong said the EC would announce the unofficial results of 350 constituency seats later on Monday, but unofficial full vote counts -- which are needed to determine the allocation of 150 other seats in parliament -- would not be available until Friday. He reiterated that official results from at least 95% of House seats would not be finalised until May 9.

On Sunday night, the EC delayed without explanation a full announcement of preliminary results as a large number of complaints mounted over apparent mistakes in the count and possible irregularities at the polls.

Nearly 1.9 million votes had been invalidated with 93% of votes counted, the EC said late Sunday. Earlier counts showed that in a handful of provinces more than half the ballots cast were invalidated.

The Election Commission has said it will finalise the results by May 9.

But questions over the count have been asked, with social media ablaze with allegations of vote buying, mass invalidation of electoral cards and bungling by polling staff across the country.

About 400,000 people signed a change.org petition to dissolve the commission.