SINGAPORE: A 60-year-old Singaporean man is under investigation for inserting toothpicks into a seat on a public bus, a suspected case of "mischief" that could put him behind bars for up to two years, the police said on Tuesday.

"Through extensive inquiries and with the assistance of CCTV footage, officers ... established the identity of the suspect," a police statement said.

Pictures of three toothpicks sticking up from the seat were posted last month by a Facebook user, who said she noticed them just as she was about to sit down.

"Remember to check your seat next time before sitting, guys!" she wrote. The post was shared more than 2,500 times.

Singapore, a wealthy city-state, has one of the lowest crime rates in the world. However, one of the government's public information slogans is: "Low crime doesn't mean no crime".

Authorities come down hard on minor crimes such as vandalism, which is punishable by caning, and the import of chewing gum is banned, in part to keep public spaces clean.

Two years ago, a smoker was fined S$19,800 ($14,550) for throwing cigarette ends out of a window of his flat for days.

The police said investigations into the case of the toothpicks were continuing. The offense of mischief carries a punishment of imprisonment for up to two years or a fine, or both.