BANGKOK (REUTERS) - The Thai political street artist who goes by the name "Headache Stencil" prefers to keep his true identity anonymous, but he is pretty sure that the authorities know where to find him.

Shortly after one of his latest public projections on the June 24, he noticed several men loitering outside his apartment.

He says security at the building told him the men had identified themselves as plainclothes police.

"Now when I leave home at night I have to look twice behind my shoulder," he said at a gallery show of his more permanent art on Friday (July 31) night.

The display of political art comes amid youth-led political protests by thousands calling for the resignation of Thai Prime Minister Prayut Chan-o-cha.

As in all his public appearances, the artist covered his face with a mask, with his public anonymity plus his work's political nature prompting some to call him "Thailand's Banksy"after the renowned British graffiti artist.

Asked whether police were monitoring the artist or knew his identity, Mr Krisana Pattanacharoen, a deputy police spokesman, said: "I don't know him at all."

Headache Stencil takes his name from the fact that most of his work is sprayed onto walls using stencils and the fact that he aims to cause headaches for Mr Prayut, who first came to power in a 2014 military coup.

"I started three days after the coup," he said of his work, adding that he had an office job before that.

Much of his stencilised street art that tends to appear overnight on walls and buildings around Bangkok mocks Mr Prayut, who he has portrayed on the face of a Rolex watch in a reference to allegations of government officials' unreported wealth.

"The more they try to suppress me, the more I would make my counter move. I won't stay still," he said.