When Mr Qiu boarded SBS Bus 30 yesterday evening (18 June), little did he expect to see a porn film on board.

Seated at the top deck of the bus was a middle-aged man watching a porn film on his mobile phone. To Mr Qiu's disgust, the man was watching the film with the phone's sound on, and the video's sound track could be heard by those seated nearby.

Mr Qiu, 37, a civil engineer, said that the man was sitting at the fourth last row on the second deck. The man looked to be about 45 years old, is of slim build and is rather short.

Angered by this indecent behaviour on board a public bus, Mr Qiu recorded the entire incident and forwarded the information to local Chinese newspaper Shin Min Daily news.

According to Mr Qiu, the film consisted of a naked couple, in which only the lower half of the man's body can be seen on the screen. The woman in the film, who had shoulder-length hair, was performing a sex act on the film's male lead.

As the phone's volume was turned up, the people nearby could clearly hear the soundtrack from the porn video.

Mr Qiu told Shin Min, "My wife was with me at that time; a mother and daughter were also seated just in front of that man. Everyone heard the video's soundtrack, and we were all every embarrassed by this entire episode

"The man watched his film for a full 10 minutes. It was only when I turned on my MP3 player to its loudest and brought it to his ear that finally made him stop."

According to the law, anyone who owns, distributes or is responsible for making pornographic material is committing an offence under the Flims' Act.

Those found guilty can face a maximum sentence of two years' jail, a minimum fine of $2,000, or both.