Suthep Thaugsuban, secretary-general of the Democrat Party, yesterday detailed how key figures of the Thai Rak Thai Party allegedly carried out a scheme to "buy" an opposition.

According to Suthep, the scheme took place from March 2 to 15 at the party's headquarters, the Defence Ministry, a hotel and a bank branch in Bangkok.

His detailed allegation followed the Thai Rak Thai's threat to launch civil and criminal suits against the Democrat Party.

Suthep said he had evidence to prove the alleged election fraud and urged the Thai Rak Thai Party to bring the case to court.

On March 2, he alleged that two key Thai Rak Thai figures met at the party's headquarters with four others to devise ways to help a group of small political parties field candidates in constituencies in four central and 14 southern provinces.

Seats in these constituencies were previously occupied by MPs from the former opposition Democrat Party, which is boycotting the April 2 election.

According to Suthep, the problem for Thai Rak Thai was that all the MP candidates to be fielded by these small parties had to be members of a political party for at least 90 days prior to application.

As a result, the plan was to replace the names of about 500 real members of political parties with new ones so that they would be eligible to run in the election.

Suthep also alleged that a computer disc containing the Election Commission's database of political party members was provided to operators of the scheme so names could be changed electronically.

"I will fully cooperate by producing the evidence to back up the allegations when the case goes to the court," said Suthep.

Meanwhile, Ong-art Kampaibul, the Democrats' spokesman, said the party would hold a rally at Bangkok's Sanam Luang on Friday to explain why it was boycotting the election.