A group of parliamentarians from Ireland and Britain witnessed 12 diesel laundering "fronts" in operation during a recent visit to the Border between south Armagh and the Republic.
The visit was part of a fact-finding mission by a committee of the British Irish Parliamentary Assembly, which will present a report on its findings in Dublin today.
It is believed the report will express alarm at the extent and scale of the fuel laundering business along the Border.
A three-man delegation from the committee, which was examining the issue of cross-Border police co-operation and illicit trade, saw two white unmarked 40-foot tankers at one of the premises it visited.
Matter of urgency
A number of smaller tankers were also spotted by the committee, which travelled incognito to the area two weeks ago.
The report has been drawn up by the committee with recommendations to the Irish and British governments on action that should be taken as a matter of urgency to clamp down on the illicit trade.
Fine Gael Senator Paul Coghlan, a member of the group which travelled to south Armagh, refused to comment on the visit but added that he would have things to say when the report was published.
The delegation met police officers on both sides of the Border who deal directly with the problem. They also met senior Garda and Police Service of Northern Ireland representatives on visits to Belfast and Dublin.
Lack of resources
It is understood the report will confirm that cross-Border co-operation between the law enforcement agencies and officials is excellent but will raise concerns about the level of resources being devoted to tackle cross-Border illicit trade.
In particular, it is believed that the report will call for an all-island approach to deal with the problem, involving the revenue authorities on both sides of the Border.
It will also recommend that a permanent full-time task force be established to eliminate the activities of organised crime gangs along the Border, with staff from all the relevant agencies including criminal asset recovery agencies.
One important challenge identified by the committee is the difficulty in bringing prosecutions and obtaining convictions against those suspected of being involved in large scale illicit trade.
The importance of this even as a purely revenue raising exercise for the two jurisdictions is highlighted.
It is believed the committee will express alarm at the evidence of the widespread presence of fuel laundering plants and filling stations selling illicit fuel in Border regions.