An escalation in antisocial behaviour on Dublin's Luas line this year has led to an increase in the number of physical attacks on its staff, the Sunday Tribune has learned.

Amid ongoing concerns about the potential impact on passenger safety, gardaí have been called in to patrol one of its services, the Luas Red line, from 8pm in the evening until the last tram departs. A spokeswoman for Veolia Transport, which operates the Luas on behalf of the Railway Procurement Agency, confirmed that to date this year, there have been 12 physical assaults on its staff. This compares with 10 such assaults during the whole of 2009. She also noted that the majority of verbal threats to staff were racist in nature.

"Antisocial behaviour is on the increase in Dublin and this is reflected at times on the Luas," she said. "Veolia Transport has witnessed a small increase in the number of assaults on staff this year… the physical assaults on staff likewise are entirely unacceptable.

"The verbal threats to staff are very demoralising particularly since the majority of threats made to staff are racist."

The spokeswoman added that since 5 August last, the garda traffic department had assigned four gardaí to the Luas Red line – which runs from Tallaght via Rialto and Heuston Station to the Point – from 8pm until the last tram. No "end date" for this operation has yet been set, she said.

She also welcomed the controversial Criminal Justice Public Order Bill 2010, which is currently before the Dáil.

"This bill contains proposals for an act which will prohibit harassment or intimidation of the public by persons who engage in begging, and will confer power on members of the Garda Siochána to give direction to people to desist from begging," she said.

"Luas is a very safe transport option. Daily 70,000 passengers travel on the Red and Green lines. Please remember, last year alone 25.4 million passengers' journeys were made. The number one priority of Veolia Transport is to operate a safe Luas service for staff and passengers. We are committed to do everything in our power to ensure this."

She added that while Veolia Transport and Luas staff – typically ticket inspectors – do not wear stab vests, the security firm STT which provides security staff on the Luas do wear protective jackets. These meet the British safety standard, she said.

Meanwhile, gardaí were last night investigating a gas explosion on Davitt Road, Drimnagh, Dublin, which resulted in the suspension of all services on the Luas Red line yesterday.