​Secretary of State Mike Pompeo called out China for trying...

Pro-democracy protesters in Hong Kong set massive street fires, trashed two subway stations and trampled the Chinese flag Sunday, in the fourth month of violence in the troubled former British colony.

Protesters occupied the New Town Plaza shopping mall in what began as a peaceful assembly — with demonstrators folding paper origami cranes and singing while backed by a small, woodwind band.

But, in what has emerged as a disturbing pattern, the gathering grew increasingly violent as the day progressed, with demonstrators placing a Chinese flag on the ground and taking turns running over it.

They defaced the flag, threw it into a dumpster and pushed it into a nearby river.

A group of hardcore protesters then spilled out into a nearby subway station, smashing surveillance cameras, busting ticket sensors with hammers and blasting ticket machines with spray paint.

Riot police dislodged the protesters — sending them back into the streets, where they built a barricade near the mall and set at least two large fires in the latest clash with officials.

Demonstrators have faced off with authorities since June over alleged attempts by the Chinese government to stifle freedoms that Hong Kong was promised when the British handed the former colony to China in 1997.

Hong Kong Chief Executive Carrie Lam withdrew an extradition bill that sparked the protests in the first place — but it has not appeased the demonstrators.

The protests have become increasingly violent in recent months. Police have used tear gas and water cannons to stifle the thousands of demonstrators, who have repeatedly set up barricades and hurled Molotov cocktails at police in riot gear.

The protests represent an international embarrassment for China’s Communist Party, which is on the eve of celebrating its 70th year in power on Oct. 1.

With Post wires