The National Bus and Rail Union (NBRU) has renewed calls for a dedicated transport police unit after a gang of youths "hijacked" a bus on the country's first 24-hour bus route and threatened the female driver with rape.

The NBRU said while it is reviewing the incident on the 220-service in Cork, the threat of service withdrawal "looms large" in the wake of several similar incidents on bus routes around the country on Halloween night.

NBRU general secretary, Dermot O'Leary, said it would be a shame if the high-frequency 220 service linking Ballincollig via Cork city to Carrigaline - which has seen a 70% surge in passenger numbers since its extension to a 24-hour service in January - were impacted by the "loutish" actions of a few thugs.

But he said: "The union will continue to monitor the antisocial behaviour and downright thuggery that has become pervasive across bus and rail services.

"The spectre of service withdrawals similar to those withdrawn on Halloween looms large over our transport system. We are now calling on all politicians from all parties and none to insist that this government acts before it’s too late."

Gardaí in Cork are investigating the incident on the 220 which occurred at around 9.30pm last Thursday - Halloween night - which will include a review of CCTV footage. They are expected to take a statement from the female bus driver tomorrow. As she arrived at the last stop in Carrigaline, a large group of teenagers boarded. Several refused to pay, they ignored the driver and went upstairs.

The driver followed them to confront them but was verbally abused.

She went back to her cab, pulled down a screen and called her supervisor for assistance. The supervisor and gardaí arrived within 15-minutes.

But during the wait, the driver was threatened with rape, gang members made gun gestures with their hands, pointing at her head, and she was subjected to "racial abuse at the extreme end of the scale".

They also kicked the door and banged the screen of the cab. Gardaí arrived and requested back-up.

The gardaí and the supervisor were also verbally abused during the incident. The supervisor described it as the "nastiest and most dangerous situation" he was ever in.

Bus Éireann confirmed that the offending teens were escorted by gardaí onto another bus, which was then driven back to the city under garda escort, and with gardaí on board.

It was 11.30pm before the incident was over. The driver has been on leave since the incident.

"Bus Éireann are fully supporting our driver at this time and are liaising with An Garda Síochána who are investigating this unacceptable incident," a spokesperson for Bus Éireann said.

"Although such incidents of anti-social behaviour are rare, not only can they cause distress to staff and customers, but they also put at risk the safety of our customers, our drivers and our fellow road-users.

"Our drivers are issued with clear instructions that if there is antisocial behaviour taking place on the vehicle they are driving, they are to immediately seek the assistance of a supervisor or the gardaí, if required, which our driver did in this case.

"If anti-social behaviour does occur on a service, we curtail the service for the safety of our staff, customers and fellow road-users."

Halloween hell: NBRU's list of service curtailments on Halloween night arising out of anti-social behaviour

Dublin Bus

Route 38/a: Buses did not serve Corduff from 8.55pm, with reports of gangs of youths, multiple fires and stolen cars in the area.

Route 39/a: Buses withdrawn from UCD campus (Belfield) at 8pm following reports of aggressiveness and crowd control issues with a large number of intoxicated students.

Route 79: Buses did not serve Spiddal Park from 8.50pm. Buses terminated at Cherry Orchard Hospital with reports of antisocial behaviour and stonethrowing.

Route 27: Buses did not serve Brookfield, with reports of stonethrowing and stolen cars set alight.

Route 40: Buses did not serve Finglas south from 8.55pm after reports of fireworks being thrown onto buses.

Bus Éireann

Route 103, Ashbourne, Co Meath: Fireworks rocket fired at bus. It exploded in the doorwell. There were no injuries.

Route 302, Limerick: Bus service pulled from 9.30pm because of constant stone and egg throwing at vehicles.

Route 303, Limerick: Buses did not serve or Marley Park from 5.15pm and did not serve Carew Park from 7.30pm. Reports that the driver and interior of bus were destroyed by eggs.

Route 304/304a, Limerick: Buses redirected from Limerick University from 8pm after what the union described as "absolute mayhem".

Route 306, Limerick: Bus did not serve Ballynanty because of stone and eggthrowing.

Route 220, Cork: Gang threaten female driver with rape, and subject her to racial abuse "at the extreme end".