A teacher at a primary school here is on leave while the police investigate a video that allegedly showed him filming up the skirt of a train commuter.

The video, posted online last Saturday, was shared widely. Netizens later linked it to a teacher at Xinmin Primary School.

The school in Hougang confirmed yesterday that one of its teachers is being investigated over the incident. He joined the school in June last year, it said.

Mr Clement Lee, the school's vice-principal, told The Straits Times that "the safety of our students is of top priority".

"The case is under police investigation and the teacher is currently placed on leave," he added.

The clip, slightly over two minutes long, shows a young man in a pink T-shirt and black shorts fiddling with his mobile phone as he stands in the train, and later placing the phone, with the camera facing up, on top of his duffel bag.

He then lowers the bag and moves it close to a woman in a skirt behind him, so it is brushing the back of her legs.

The clip was taken while the train was between MacPherson and Paya Lebar stations on the Circle Line.

A Facebook user who posted it on a public group said it had been sent to him by a friend.

According to him, the friend felt something was amiss when the man placed his phone on top of his bag, and began recording the whole incident.

Upon viewing the clip after getting off the train, said the Facebook user, his friend realised the man may have been taking a video.

Police confirmed that a report had been lodged and investigations are ongoing.