Police fired water cannon at anti-government protesters in Bangkok, Thailand on Friday night (October 16).

Onlookers hit by the water claimed it contained irritant chemicals.

Large crowds gathered in the Pathum Wan area after a previously planned location at the Ratchaprasong Intersection was closed by police.

Prime Minister Prayut Chan-o-cha ordered roads to be blocked around the area and warned a curfew could be imposed if protests escalate.

Public transports, including metro and sky trains in the area, have also been closed. Anti-government rallies stared on Tuesday and sparked clashes with police and security personnel the next day.

On Thursday morning, dozens of Thai protest leaders were arrested and refused bail. Prime Minister Chan-o-cha declared a state of emergency following the unprecedented unrest. The law bans gatherings of more than five people.

Thai anti-government and pro-democracy protests have grown since the start of the year.

Activists have made sweeping demands including the resignation of the prime minister, constitutional changes and reform of the monarchy.

However, officials have claimed that a mixture of disaffected opposition, foreign influence and social media "bots" are stirring up the unrest.