EU Agriculture Commissioner Phil Hogan has challenged Sinn Féin to "tell more of what they know" about border fuel rackets.
Mr Hogan said it was plain that fuel smuggling and laundering was being carried out by criminals with links to so-called "dissident republicans".
But, without specifically mentioning Sinn Féin, he raised questions about these dissidents' links to the political system, north and south.
"It is clear the criminal gangs involved in fuel rackets have breakaway paramilitaries among their members.
"Some of these are close to the political process and some of their windfall gains may be making their way into the political process," Mr Hogan told the Irish Independent.
Asked if he was specifically accusing Sinn Féin and raising questions about the IRA, the Commissioner replied: "Well, I think that Sinn Féin in government in the North could be more assertive in bringing the people involved in these rackets to heel. I think they should tell us what they know."
After a visit to the North, Mr Hogan said Belfast political sources had told him the fuel rackets were worth some Stg£38m (€50m) per year.
And he warned that the fallout from environmental problems associated with abandoned fuel effluent now risked doing huge damage to the reputation of Irish food on global export markets.
Mr Hogan said the potential tragedy of this risk to Ireland's global food image was that it came at a time of unprecedented export opportunities for products from both sides of the border.
The Irish Commissioner said he will speak to the EU Environment Commissioner, Karmenu Vella of Malta, on how best to provide assistance to the Irish and British authorities.
"Both national authorities are well aware of this terrible problem for decades and they are trying, but not really succeeding in stopping it.
"We must now see what resources they need to help," Mr Hogan said.
The Agriculture Commissioner said the risk of pollution from recklessly discarded fuel effluent from "laundered" fuel was a huge periodic problem in many areas within a 30-mile radius on both sides of the border.
Officials recently discovered a fuel-laundering plant close to a public water supply for Armagh and Monaghan. The discovery included toxic sludge.