A graffiti, drawn by an American man in his 30s, is seen in this file photo. Courtesy of the Seoul Yongsan police station

An American man in his 30s has been booked for investigation on charges of writing graffiti in some 150 places across Seoul's Yongsan district, police said Monday.

The U.S. national is accused of jotting down words like "bruxism" or "brux" in English and Korean, using red spray paint and markers in 155 locations, including on the gates of private residences, underpasses and utility poles.

The man reportedly committed the same crime when he visited the country last year.

The suspect, who came to South Korea in October for tourism, told police he had painted the graffiti to raise awareness of bruxism, a condition referring to the grinding or clenching of one's teeth.

The police detained the man on charges of destruction and damage of property Saturday after identifying him through surveillance cameras and banned him from leaving the country.

The police plan to look into his exact motive and account of the crime. (Yonhap)