Vandals placed a giant snowball in front of a Luas tram in Dublin at the height of last Thursday's snow storm, forcing passengers to get out and walk home to their destinations after services were curtailed.

The incident, which occurred on the Luas green line at around 3.45pm near Milltown bridge, has prompted Luas operator Veolia to appeal to members of the public not to make life more difficult for its staff and customers by increasing the risk of delays.

Jennifer Stevens, who was a passenger on the Luas line when the incident occurred, told the Sunday Tribune that the tram appeared to have run over the giant snowball which in turn damaged part of the undercarriage.

"The services had been running fine up until then and after that they didn't run again," she said.

A contributor to another online discussion board also recalled an announcement being made over the intercom at the Windy Arbour stop that "some kids had put a big snowball on the track… [The Luas operator] claimed [the stoppage was due to] a big snowball, then adverse weather conditions. Most of us had to walk the remainder of the journey into town along the track anyway. It was like a very snowy Stand By Me."

A spokeswoman for Veolia confirmed that the service had been interrupted on Thursday as a result of a snowball being placed in front of the tram, but could not say how long the delay was for. This was because services were subject to more general disruptions due to snow levels on Luas tracks.

"There was a snowball on the tram line, and the obstacle detector on the tram caught the snowball. This brought the tram to a stop and caused a delay on the line," she said.

"It was a manmade snowball. It goes without saying that people should stay away from the Luas tracks and should not be placing objects in the way of trams.

"It is not funny to be throwing snowballs at trams, or to be making snowballs and putting them on the tracks."