Paramilitary groups may be involved in the cross-border disposal of illegal waste, MLAs have been warned.
Criminal Justice Inspection chiefs told the environment committee the dumping of waste - which can earn high profits - was more organised than initially believed.
Their warning came after a report earlier this year found the regulation of waste here is highly vulnerable to criminality but that at present the punishment does not 'fit the crime'.
Yesterday CJI chief inspector Brendan McGuigan said environmental crime is among "some of the most serious crime going on here".
Criminals and unscrupulous operators are making significant profits from illegal waste disposal and "going to extreme lengths, including violence, to ensure their criminal enterprises deliver the maximum return," he said.
There used to be a perception that cross-border dumping often involved landowners or someone with control and access to land "trying to make some quick money out of it".
But, responding to questions from the SDLP's Alban Maginness, he said CJI had learned that operations are more organised and criminals are constantly thinking how they can thwart new systems and rules.
Mr Maginness said it was "a public scandal" that illegal waste dumping has "allowed people to reap huge benefits, in terms of money, and destroy our environment at the same time".
Environmental crime had "gone on for a number of years" and he believed a "lack of linkage" between environmental groups had contributed to the problem.
Deputy chief inspector James Corrigan said he "couldn't rule out paramilitary involvement" in illegal waste disposal.
"The sanctions aren't effective enough to deal with the profits...anyone that wants to make profits and have a relatively low chance of being prosecuted, this is an area they will obviously look at," he added.
CJI wants to see "a strategic assessment of the waste sector" and partnership model alongside the National Crime Agency to help secure more convictions and lead to the confiscation of assets.
Their appearance yesterday came after CJI NI recommended the Northern Ireland Environment Agency (NIEA) develop a 'more rigorous' approach to dealing with offenders involved in waste crime following the report by Chris Mills, a former director of the Welsh Environment Agency.