Prime Minister Anutin Charnvirakul has insisted he will not withdraw a defamation lawsuit against iLaw director Yingcheep Atchanont over allegations linked to the 2024 Senate election, saying legal action is the right of those affected.

Speaking at Government House on Thursday, Mr Anutin rejected calls from the opposition for him to show leniency towards Mr Yingcheep, who urged the Bhumjaithai Party to reconsider the lawsuit over iLaw's presentation of information concerning alleged manipulation of the Senate election.

Mr Anutin said the case was a personal matter for those who believe they had been unfairly accused, adding that Bhumjaithai members could decide individually whether to pursue legal action.

PM's Office Minister Paradorn Prissananantakul said the decision to sue rested with Bhumjaithai, adding that he believed Mr Yingcheep should have considered the impact of publishing the allegations.

In an earlier Facebook post, Mr Yingcheep urged the Bhumjaithai Party to drop its planned defamation lawsuit, saying criminal defamation was not the proper way to settle public disputes. He said the allegations of Senate election vote-rigging had already been raised publicly by witnesses and others with knowledge of the case, and called on the party to rebut the claims publicly rather than pursue legal action, leaving the public to judge the facts.

iLaw, a Bangkok-based non-profit organisation focused on legal and democratic reform, released information alleging possible links between nine current and former Bhumjaithai politicians and a suspected network involved in manipulating the 2024 Senate election.

Mr Yingcheep on Tuesday submitted information to People's Party list MP Parit Wacharasindhu, chairman of the opposition whip, on alleged candidate coordination, voting patterns and payments at local and national levels.

The organisation alleged that the prime minister and eight other politicians played various roles in the alleged Senate election vote-rigging scheme, as per:

Anutin Charnvirakul -- iLaw alleged Mr Anutin attended a meeting of newly elected senators at the Pullman Bangkok King Power Hotel after the national selection.

Songsak Thongsri -- It alleged Mr Songsak was linked to organising Senate candidates and coordinating activities in several provinces before the election.

Paradorn Prissananantakul -- It alleged Mr Paradorn helped plan and manage a network to support Senate candidates and coordinate their campaigns.

Korrawee Prissananantakul -- It alleged Mr Korrawee was involved in planning the alleged Senate election operation and coordinating candidates through associates.

Phiphat Ratchakitprakarn -- iLaw alleged Mr Phiphat had personal and political links to several successful Senate candidates and their coordinators.

Napintorn Srisunpang -- It alleged Mr Napintorn met Senate candidates before the national selection to discuss matters related to the Senate election.

Suksomruay Wantaneeyakul -- iLaw alleged Ms Suksomruay acted as a coordinator for Senate candidates in Amnat Charoen.

Phichai Chomphuphon -- It alleged Mr Phichai's aides helped recruit and support Senate candidates in Surat Thani.

Supachai Phosu -- It alleged Mr Supachai attended a meeting where Senate candidates prepared voting lists ahead of the national selection.