BANGKOK (BLOOMBERG) - Thailand's Parliament is set to vote on a roadmap for constitutional amendments on Wednesday (Nov 18), a day after the most violent anti-government protest in years left more than 50 people injured.

Lawmakers will vote on how to amend the charter, one of the key demands of pro-democracy groups, who are also calling for monarchy reform and the resignation of Prime Minister Prayut Chan-o-cha.

On Tuesday, a rally near the Parliament turned violent after the police fired water cannons mixed with irritants to disperse the crowd and some pro-government supporters clashed with the protesters.

The youth-led groups have called for another gathering in Bangkok on Wednesday to pressure lawmakers into considering their demand for a major rewrite of the Constitution.

The clashes point to an escalation in the months-long movement, with pro-establishment groups staging regular demonstrations too.

"If the Parliament doesn't accept the amendment that the people want, there'd be no more compromise," Free Youth, one of the protest groups said on Facebook. It said charter should be amended to bring the monarchy under the Constitution.

The Parliament vote on charter pathway is yet another attempt at placating the protesters, who have broken long-held taboos about publicly criticising the royal family and questioning laws that stifle discussion of the monarchy.

While the lawmakers may vote to amend the charter, political analysts say changes likely won't address all of the demands from the protesters.

Thailand's current charter has been the point of contention since its inception after Mr Prayut, a former army chief, took power in a 2014 coup.

Protesters and critics viewed it as instrumental in helping the royalist establishment retain its grip on power, with Mr Prayut returning as the leader after the 2019 elections.

The charter allows the military-appointed Senate, whose powers protesters want scrapped, to vote for the premier.