BANGKOK (Reuters) - Thailand's disbanded opposition Move Forward unveiled a new leadership and political vehicle on Friday that will become the biggest party in parliament, naming it People's Party, and promising to advance its predecessor's progressive platform.

The anti-establishment Move Forward, which won most seats in the last election but was blocked from forming a government, was dissolved by the Constitutional Court on Wednesday, which ruled its plan to amend a law that shields the royal family from criticism risked undermining democracy and the constitutional monarchy.

All 143 surviving Move Forward lawmakers have joined the new party to be led by 37-year-old Natthaphong Ruengpanyawut, a former executive of a cloud software company who joined Move Forward in 2019.

"We will carry on Move Forward's ideology. The mission for me and the party is to create a government for change in 2027," Natthaphong told a press conference.

The dissolution, which was criticised by the United States, Britain and European Union, was the latest salvo in a two-decade battle for power in Thailand that broadly pits its conservative establishment and royalist military against popularly elected parties.

Move Forward's liberal agenda has won massive support from young and urban voters, but earned it some powerful enemies, with plans that include reforming the military and dismantling business monopolies worth billions of dollars each year.

Its bid to amend a law on royal insults was its undoing, riling influential generals and royalists with far-reaching connections, who see the monarchy as sacrosanct.

Though the court in a January ruling ordered Move Forward to drop its campaign, Natthaphong said the new party would continue the push to change the law, known as article 112, though with caution.

Thailand's lese-majeste law one of the world's strictest of its kind, with punishments of up to 15 years for each perceived insult of the crown. The palace typically does not comment on the law.

"We have said we propose to amend article 112 to ensure that this law is not a political tool used to abuse others, but we won't be careless," Natthaphong said.

"I think we will continue to push for the improvement and fixing of this law, which is still problematic."

Nattapong is a graduate in computer engineering and was Move Forward's deputy secretary-general, working on the party's digital policies, which were key to its election win.

The People's Party is the third incarnation of the Future Forward, which was dissolved for a campaign financing violation in 2020, triggering nationwide anti-government protests.

The English name People's Party was commonly used by the Khana Ratsadon, which launched a 1932 revolution that ended the country's absolute monarchy.