Thailand's most popular politician was banned from politics for 10 years and his party dissolved on Wednesday over his attempt to reform the kingdom's archaic royal defamation laws.

The Constitutional Court in Bangkok voted "unanimously" to dissolve the Move Forward Party (MFP) and ban its executive board, which includes its former leader Pita Limjaroenrat, for 10 years, judge Punya Udchachon said.

Pita, 43, led the reformist MFP to a shock first place in a general election last year. He struck a chord with young and urban voters with his pledge to reform Thailand's strict royal defamation law, which rights groups say has been misused to stifle pro-democracy groups.

His bid to become prime minister was blocked by conservative forces in the Senate. A coalition of army-linked parties took office instead under Prime Minister Srettha Thavisin.

Pita's political career was shaken further in March when Thailand's election commission asked the top court to dissolve the MFP.

That followed an earlier ruling that the party's pledge to reform the lese-majeste law amounted to an attempt to overthrow the constitutional monarchy.

Lese-majeste charges are extremely serious in Thailand, where King Maha Vajiralongkorn enjoys a quasi-divine status that places him above politics.

A few dozen supporters dressed in the party's trademark orange gathered in front of MFP headquarters in Bangkok, according to an AFP journalist.

Siriporn Tanapitiporn, a 53-year-old food market vendor, cried after the verdict was read.

"But I have faith in the younger generation, they will return the democracy back to our country," she said.

Sakhorn Kamtalang, 60, said the court didn't have the right to dissolve the party.

"To me, Pita is my PM. The current PM is just a salesman, who isn’t fit as the country leader," she said.

Hua Jaidee, a 69-year-old university housekeeper, said "good people always end up being bullied".

Pita appeared in parliament in high spirits earlier on Wednesday, telling lawmakers he had faith in the kingdom's legal process.

He warned against the weaponisation of Thailand's judicial system, saying in an interview with AFP before the ruling that 33 parties had been dissolved over the past two decades, including "four major ones that were popularly elected".

"The issue is not what we will do if we are dissolved -– that is already taken care of and our ideas will survive -- but rather the pattern of weaponising the judiciary and independent bodies that we should pay attention to," he said.

"We should not normalise this behaviour or accept the use of a politicised court as a weapon to destroy political parties."

The MFP has 148 seats in Thailand's 500-seat parliament and Pita said its executive would form a new vehicle if the party was dissolved.

Pita first appeared on the political scene in 2018 as part of the progressive Future Forward Party (FFP), which was dissolved in 2020, sparking mass youth-led demonstrations that shook Bangkok for months.

Tens of thousands took to the streets at the height of the protests, many making unprecedented public criticism of the royal family as well as demands for transparency and reform.

More than 270 people were charged with lese-majeste after those protests, including two elected MPs.

"While I cannot and will not stop peaceful assembly -- which I fully support -- it is the right of people in a democratic system to express opposition to anything they see as unjust," Pita said.

New York-based Human Rights Watch (HRW) says the lese-majeste law has been routinely used to silence political dissent.

Thai authorities prosecuted at least 258 people last year on lese-majeste charges in relation to activities undertaken at democracy protests or comments made on social media, HRW said in its 2024 World Report.

Thailand, Southeast Asia's second-largest economy, is known for its chronic instability, with a dozen coups since the end of absolute monarchy in 1932.