BANGKOK, Apr. 3 (Reuters) - Thailand's Constitutional Court on Wednesday said it had accepted a case seeking the dissolution of the opposition Move Forward Party, in another blow to a popular anti-establishment movement pushing major institutional reforms in the country.

The court agreed to take on the complaint filed by the election commission asking to disband Move Forward for its controversial campaign to reform a law that shields the powerful monarchy from criticism, under which at least 260 people have been prosecuted in the past few years.

The case came after a January ruling by the same court that found Move Forward's plan to amend the law was unconstitutional and tantamount to an attempt to overthrow the system of government with the king as head of state. Move Forward has rejected that.

Move Forward pulled off a stunning feat in winning last year's election but was blocked from forming a government by lawmakers allied with the royalist military. It is the biggest party in the lower house with about 30% of seats.

Its platform of institutional reform resonated among young and urban voters, including a plan to amend the law protecting the crown, which carries a punishment of up to 15 years jail for each perceived insult of the royal family.

Thailand's monarchy is constitutionally enshrined to be held in a position of "revered worship" and many royalists see the law as sacrosanct. The palace typically does not comment on the law, which is among the strictest of its kind in the world.

If the court rules against Move Forward, it faces dissolution and lengthy political bans for the its leadership, the same fate suffered by predecessor, Future Forward, after it was dissolved in 2020 over a campaign funding violation.

A similar complaint has also been filed with a Thai anti-graft body seeking life bans for 44 of the party's current and former lawmakers.

Move Forward's agenda and bid to curtail business monopolies has threatened to upend Thailand's conservative status quo, and led to a once-unthinkable governing alliance between the populist Pheu Thai and parties backed by its bitter enemies in the military.

Activists say the lese-majeste law has been used to smear progressives and stifle institutional reforms. Move Forward has argued its campaign sought to strengthen the constitutional monarchy and prevent the law from being misused.

Its former prime ministerial hopeful Pita Limjaroenrat last month told Reuters his party would "fight tooth and nail" for its future amid efforts to bring down the party, which he said showed paranoia by Thailand's conservative establishment over its push for reforms.