Dublin Bus has begun an investigation into the unofficial dispute by militant bus drivers early last week which cost the company over €400,000 and left around 140,000 commuters stranded.

"All aspects of the dispute will be looked at and we will see where that will take us," a spokesman for Dublin Bus said last week. It is understood that dismissal of the drivers – members of the Dublin Bus Workers Action Group (DbWag) – who sparked the wildcat action has not been ruled out.

But the prospects of the state bus company recouping lost income are remote. Normally, an employer subjected to unofficial action can sue the union involved. But in this case the two unions representing the 3,600 Dublin Bus drivers – Siptu and the Nbru – were not involved and tried to distance themselves from the action.

DbWag is part of the international Socialist Workers' Party. Owen McCormack, a member of the SWP, heads the group and led the last strike at Harristown bus depot over a year ago in November 2007. Bus driver John McCamley was also a key figure in last week's strike even though his father, Bill McCamley, also a driver with Dublin Bus based in the Phibsborough garage, is a worker director of the company.

DbWag organises within trade unions, exploiting the disaffection of workers against what the SWP regard as the sell out of trade-union leaders to capitalism.

"Ireland needs more rebellions like that of the busworkers. That way we would not have politicians boasting to their counterparts in Europe that they have been able to get away with wage cuts which in other countries would have led to riots," the SWP said in a statement last week.

"We argue for solidarity action between workers and oppose the idea of social partnership," according to the SWP's policy statement.

It uses various 'workers action groups' to foment opposition to partnership, particularly at a time when partnership is under threat as it is at the moment.

The group has been based in Harristown for a number of years now but also organises within key union branches such as Siptu's education branch.

The group has a bad relationship with the Nbru, whose general secretary, Michael Faherty, accused DbWag of "hijacking" the very real concerns of the union's members and of promoting their own political agenda.

This fractious relationship descended into farce during a dispute in November 2007, which centred on a requirement for drivers of a new route to come back to the Harristown garage for their break rather than take it in the city centre. Dublin Bus's policy is to build garages on the outskirts of the city which means workers are split up and can no longer gather in city-centre canteens.

Consequently, DbWag's influence is now largely limited to Harristown.