A photograph of two train vandals was posted to rail operator SMRT's Facebook page on Tuesday (Oct 4) morning, Chinese evening paper Shin Min Daily reported.
It was captioned with a taunt: "Was very nice to spraypaint your smrt Train! thanks singapore!"
The picture on SMRT's Facebook page, which depicts two men posing on the tracks in front of a train, was shared by a user going by the name "Elton Henrys". The paper reported that the picture has since been removed.
In November 2014, German nationals Elton Hinz and Andreas Von Knorre broke into SMRT's Bishan Depot on three occasions.
Hinz and Von Knorre, who had been working in Australia, bought 12 cans of spray paint and yellow latex gloves upon their arrival in Singapore.
During their third intrusion at the depot, they took a photo together and spray-painted a train carriage with 10m-high graffiti.
SMRT spent $13,650 on the clean-up operation for the train, which was out of commission for over a week.
Within weeks, the duo were tracked down by the Thai police, arrested by the Malaysian police, and extradited to Singapore. They were sentenced to nine months' jail and three strokes of the cane last March.
Earlier this year, footage was leaked of a previous SMRT vandalism incident in 2011, where the perpetrators were never apprehended.
American couple Jim Clay Harper and Danielle Bremner posted a video this April showing two masked figures cutting a hole in a fence and spray-painting a train.
SMRT was fined $200,000 for that security breach.
In 2010, Swiss national Oliver Fricker and Briton Dane Alexander Lloyd carried out a similar crime at SMRT's Changi Depot.
Fricker received seven months' jail and three strokes of the cane, but Lloyd was never caught. SMRT was fined $50,000.