Forensic police have found no trace of gunpowder in what looked like a small bullet hole at the house of Pheu Thai Party member Ruengkrai Leekitwattana.
Police from the Forensic Science Division and Bang Sue station went to his house on Monday after the party's legal team member filed a complaint that his house had been shot at on Sunday.
Mr Ruengkrai found the hole in a glass window on the second floor of the house in Soi Intamara 1 in Phaya Thai district. It was about 8 millimetres in diameter, police said.
Bang Sue police chief Pol Col Seksit Supa-uan said after the visit that the forensic team did not find substances indicating a bullet was fired at the building.
Forensic officials believed the hole might have been caused by a slug fired from an air gun by someone hunting birds accidentally hitting the three-story house, he added. The ballistics and absence of gunpower indicated that it was not life threatening.
Mr Ruengkrai, a key Pheu Thai member who closely monitors all projects by the government, said he was relieved to learn the shot was not politically motivated.
Deputy Prime Minister Prawit Wongsuwon said the government would provide security for him if requested.