Thai democracy protesters will return to the streets of Bangkok Wednesday, a day after six people were shot with live rounds in violent clashes, as lawmakers vote on possible constitutional reforms.

On Tuesday in the most violent confrontations seen since the pro-democracy movement kicked off in July, police used tear gas and water cannon on demonstrators, and protesters clashed with royalists near parliament.

The vote comes a day after the most violent clashes since the pro-democracy movement kicked off in July
The vote comes a day after the most violent clashes since the pro-democracy movement kicked off in July AFP / Jack TAYLOR

Prime Minister Prayut Chan-O-Cha has urged protesters to refrain from violence, but ruled out introducing another emergency decree -- like the one banning public gatherings of more than four people which spanned a week in October.

"No need. It affects the country stability and confidence. No-one will want to come or invest here because our confidence has been eroded," Prayut told reporters.

Some in the crowd were shot Tuesday night, but it was unclear who opened fire.

Royalist supporters facing off against police in Bangkok
Royalist supporters facing off against police in Bangkok AFP / Mladen ANTONOV

Bangkok police deputy commissioner Piya Tavichai said officers are investigating the shootings, which happened about 300 metres (yards) from the main protest zone.

He said one royalist supporter was shot in the hip and a pro-democracy protester in the leg.

A pro-democracy protester hugs a royalist supporter on the front line of clashes in the Thai capital
A pro-democracy protester hugs a royalist supporter on the front line of clashes in the Thai capital AFP / Mladen ANTONOV

"The rest of shooting victims are still under investigation, but the fact was both sides were shot and wounded," he told reporters Wednesday.

Bangkok has been rocked since July by youth-led rallies demanding a constitutional overhaul and the removal of Prime Minister Prayut Chan-O-Cha, who took power in a 2014 coup.

Some in the movement have also called for reforms to the monarchy -- a once-taboo subject.

A policeman rinses tear gas from his eyes during the huge protest in Bangkok
A policeman rinses tear gas from his eyes during the huge protest in Bangkok AFP / Jack TAYLOR
Thai democracy activists vow to return to the streets after police fired water cannon and tear gas on demonstrators in the most violent clashes seen since the protest movement erupted in July.
Thai democracy activists vow to return to the streets after police fired water cannon and tear gas on demonstrators in the most violent clashes seen since the protest movement erupted in July. AFPTV / Pitcha DANGPRASITH

On Tuesday, as lawmakers debated possible changes to the military-scripted constitution, protesters ploughed through police barricades towards parliament, prompting the use of tear gas and water cannon.

More than 50 people were injured, mostly by tear gas, according to an ambulance and medical coordination service, which said six people were shot.

Police have denied officers used rubber bullets or live rounds.

The Thai Human Rights Lawyers Association slammed police tactics, saying they were "not in accordance with international procedure to disperse demonstrations".

Thai MPs have been discussing various proposals for constitutional change, which mostly exclude any reform to the monarchy.

One proposal seeks to replace the military-appointed Senate with directly elected representatives.

It was Senate support that allowed Prayut to hold on to power after last year's election.

Parliament began voting Wednesday on which amendments are to be debated further.

The vote is expected to take several hours and may not be finished by the time protesters regroup at a major intersection in Bangkok's shopping district of Ratchaprasong at 4:00 pm (0900 GMT).

"We will open a new era in our fighting," prominent student leader Parit "Penguin" Chiwarak told the crowd on Tuesday.

A heavy police presence is expected with several thousand officers deployed and four major intersections to be shut down.

A police headquarters is near the protest site and officers can be seen moving in water cannons and equipment to fortify the complex.