A Chinese farmer who pinched a bag from a fellow Singapore Airlines passenger was jailed for a year on Thursday.

Jiang Zhijun, 32, pleaded guilty to stealing Mr Pascal Blanchet's trolley bag on a flight from Singapore to Surabaya, Indonesia, at about 8.45am on March 25. He also admitted trying to steal another from businessman Krishnan Suppaiah beforehand.

Deputy Public Prosecutor Dwayne Lum told the court how Jiang opened the overhead compartment and tried to steal Mr Suppaiah's black trolley bag but was spotted by the 40-year-old Singaporean who took his luggage back from him.

Jiang returned to his seat but about 15 minutes later Mr Suppaiah saw him walking up and down the plane's aisle before taking another black trolley bag from an overhead compartment and carrying it into the toilet.

Mr Suppaiah alerted two cabin crew, who found that the bag belonging to Mr Blanchet - a 48-year-old French national - was missing. They went to confront Jiang but he refused to open the toilet door.

About 20 minutes later, he opened it slightly and two crew members managed to get in and take the trolley bag back from him.

The pilot reported the matter to Indonesian authorities who denied entry to Jiang. He was sent back to Singapore where he was arrested upon arrival.

District Judge Low Wee Ping told the Henan native: "Once we could travel in a plane, assured that our luggage was safe. Now, because of you and similar offenders, our in-flight belongings are no longer safe. The courts have been imposing deterrent sentences, yet you continue to commit these offences."

The maximum penalty for theft is three years' jail and a fine.