The decision to block the Dunsink lane through-road was taken because of concerns by various State agencies, including gardaí, customs officers and waste-enforcement council staff, about the level of criminal activity in the area, as well as illegal dumping.
It was taken following a meeting earlier this summer which was called by the Minister of State for housing, Mr Noel Ahern, who is a local TD.
Amid the ongoing crisis and protests from the Traveller community, Mr Ahern defended the decision to close off the lane as being the "only option" open to clamp down on alleged illegal activity in the area, such as diesel-laundering and the supply of firearms.
While illegal waste is the main criminal activity, Mr Ahern said other forms of activity were also a serious problem and that various attempts over the last two years by a task force involving gardaí and local authorities to tackle them had been unsuccessful.
"I fully support the action taken by Dublin City Council to close the road," Mr Ahern said. "It's not taken lightly. There was a list of troubles in the area, where quality of life of both the Traveller community and the settled community was being severely affected."
Mr Ahern also claimed that some Traveller families had been "under severe intimidation" by those engaged in illegal activity.
Various other attempts to target alleged illegal activity failed, he said, including installing close-circuit monitoring, which was destroyed within 24 hours. However, representatives of the Traveller community questioned why the Garda and other authorities felt the need to erect a concrete barrier rather than carry out standard enforcement procedures.
Mr Paddy McDonagh, a spokesman for the families, said an entire community was being punished for the actions of a few criminals within a wider law-abiding community.
The barrier means that Dunsink residents have to take a round trip of eight miles by vehicle to shops and schools in Finglas which, by using the now-blocked road, are less than a mile away.
"If there is any criminal activity, then it should be dealt with according to the law," Mr McDonagh said. "If people are dumping illegally or involved with other criminal activity, then they should be dealt with. Other families shouldn't have to suffer."
Asking whether the authorities would block off a road in a settled community area for similar reasons, Mr McDonagh said the Garda had expended huge resources on policing their protest, yet appeared unable to tackle criminal activity in Dunsink.
Officials and gardaí were unwilling to comment publicly about the background to the measures because of concerns that they would exacerbate the situation. However they were adamant that the situation had become so severe, they were left with little option.
They referred to an incident last year when a Fingal County Council official was shot at and said council officials and their families had been threatened.
Those working in the area also said they had been told by Traveller families that they had also been intimidated by the individuals behind the criminal activity. "This is about a lot more than illegal dumping," said one official. "The place is a disaster zone, possibly the worst hotspot for criminal activity on the outskirts of the city."The Revenue Commissioners confirmed that customs officers had carried out raids in the area checking for laundered fuel and car tax and had made a number of seizures and fines.