The ruling Pheu Thai Party shrugged off the latest petition against the party, saying it can address every issue raised and stressed that some of the claims are without merit.
Chousak Sirinil, the party's legal adviser, said on Friday that the six accusations made against the party lack sufficient grounds to be considered actions aimed at undermining the constitutional monarchy.
He said the petition, filed with the Constitutional Court on Thursday by lawyer Teerayut Suwankesorn, tried to portray Pheu Thai's actions as similar to those that led to the court's ruling against the now-dissolved Move Forward Party (MFP).
"It's far from the facts, and these are completely different matters," Mr Chousak said.
Mr Teerayut, who successfully sought the disbandment of the MFP, asked the court to stop former prime minister Thaksin Shinawatra from taking any action to undermine the monarchy.
According to the petition, Thaksin used the Ministry of Justice under the Pheu Thai-led government to secure an extended stay at the Police General Hospital when he should have been in jail following his conviction for abuse of power last year.
Thaksin ordered Pheu Thai to join forces with the People's Party to push for constitutional amendments. The latter is the new incarnation of the MFP, which was dissolved by the Constitutional Court after being found guilty of undermining the constitutional monarchy.
The former premier also held talks with coalition parties about who would succeed former prime minister Srettha Thavisin on Aug 14 after Mr Srettha's removal from office.
Mr Chousak said Thaksin places the highest importance on the institution of the monarchy, and he once stressed that Chapters 1 and 2 of the charter must remain untouched.
The Pheu Thai-led government and the party have not engaged in any activities that undermine the institution, he insisted.
He clarified that the party's bid to revise the ethical standards of politicians is not aimed at abolishing the code of conduct but rather at clearly defining those standards.
On Thaksin's alleged interference in the selection of the premier, Mr Chousak said Pheu Thai was independent and chose its leader, Paetongtarn Shinawatra, as its prime ministerial candidate for the House to vote on.
He said the court has yet to decide whether to accept the petition for consideration and if the case is accepted, he will lead the legal team to defend the party.
Somkid Chueakong, the prime minister's deputy secretary-general for political affairs, said Mr Teerayut's petition will not disrupt the government's work and noted that the move is driven by political interests.
Former red-shirt leader Jatuporn Prompan said yesterday the petition's core issue is Thaksin's extended stay at the Police General Hospital, which is being investigated by the National Anti-Corruption Commission (NACC).
"While the NACC probe focuses on the Corrections Department and the Police General Hospital, Mr Teerayut's case targets Thaksin and Pheu Thai.
"Still, the two don't overlap and are related to the findings of the National Human Rights Commission [NHRC], which is considered important evidence," he said.
Mr Jatuporn said he believed the court would accept the petition for review.
Former Deputy Prime Minister Wissanu Krea-ngam denied claims on Friday that he was involved in a plan to help Thaksin avoid serving time in prison. He was responding to questions asked by Sondhi Limthongkul, a former leader of the now-defunct People's Alliance for Democracy.