Parliament workers put the finishing touches to the hall where MPs-elect will be registered, even though it remains unclear whether all 500 seats in the House of Representatives will be filled.

"I share the public sentiment that the EC always sides with the ruling party," Democrat secretary-general Suthep Thaugsuban said.

The Democrat's legal team would soon recommend whether to take the EC to court after it made an arbitrary decision in favour of Thai Rak Thai leader Thaksin Shinawatra, Suthep said.

Television news clips showed Thaksin and his mother-in-law Pojanee na Pomphet handing out T-shirts with a campaign message "Thaksin Fight Fight" to their supporters but the EC ruled it had found no evidence of electoral violations, Suthep said.

Under the election law, candidates are banned from handing out gifts, an offence classified as vote-buying punishable by mandatory disqualification - known as being "red carded". Democrat Party spokesman Ong-art Klampaiboon said the EC failed to investigate a number of allegations of campaign fraud in order to help the ruling party secure victory.

Key complaints included the fielding of candidates from certain small parties that had never campaigned in past elections, he said.

Many small parties acted suspiciously regarding the funding of their candidates but the EC neglected to look into the matter, he added.

The EC also appeared to overlook the fact that many candidates from small parties registered in new constituencies after they were disqualified in their original constituencies, he said.

Democrat executive Sathit Wongnongtoey said he viewed the EC as trying to help Thaksin cling to power instead of doing its job of ensuring a free and fair vote.

Sathit said the EC and the ruling party tried to blame the Democrats for causing the electoral problems.