Friends of the Earth is renewing its legal bid to force a halt to sand dredging from Lough Neagh, it emerged on Tuesday.
The environmental group wants an urgent hearing at the Court of Appeal amid claims that the extraction of up to 1.5m tonnes a year is harming the UK's largest fresh water body.
Last year the body failed in a judicial review challenge to how a former Stormont Minister dealt with the situation.
The case centres on the decision to issue an enforcement notice rather than order an immediate stop to the dredging.
The move in 2015 by Mark H Durkan during his tenure as Environment Minister enabled sand companies to continue pending a challenge with the Planning Appeals Commission (PAC).
In November a judge rejected claims that the decision amounted to Mr Durkan effectively giving consent by "turning a blind eye" to the practice.
Mr Justice Maguire held there was legal authority for the conclusion reached after consideration of the issue.
But Friends of the Earth has now lodged appeal papers in a bid to have his ruling overturned.
James Orr, the group's Northern Ireland Director, said: "We believe the judge erred in law and didn't take into account the significance of this major nature reserve.
"The decision gives any operator very dangerous rights to destroy a designated site like Lough Neagh without any sanction."
Mr Orr added: "We are seeking an expedited hearing given there is ongoing unauthorised extraction, and we hope the Court of Appeal recognises this is an urgent situation that requires a remedy."
Sand traders have been carrying out extraction work on the Lough, a designated Special Protection Area due to its wintering population of birds, since the 1930s.
No planning permission for dredging has ever been sought or obtained.
However, firms have been able to continue activities pending the outcome of their appeal to the PAC on the enforcement notice.
Friends of the Earth mounted a judicial review challenge, claiming the failure to halt extraction brought planning laws in Northern Ireland into ridicule.
Counsel for the group likened the alleged breach to something from a primitive dictatorship.
The court heard Lough Neagh has internationally recognised environmental significance, and been classed as an area of special scientific interest.
It was contended that under Environmental Impact Assessment law the Minister acted unlawfully.
But lawyers representing the Department of Agriculture, Environment and Rural Affairs contended that the environmental group had "grossly overstated" the impact of dredging on Lough Neagh.
The court also heard sand dredging firms have spent £500,000 on studies to back their case that they are causing no environmental harm to Lough Neagh.
Steps have been taken to ensure they have authority for both retrospective and future extractions, the companies' legal representatives submitted.
Dismissing the judicial review challenge in November, Mr Justice Maguire held that the Minister's objective was to secure a situation where steps were taken to ensure the situation had to be confronted by the dredging firms.
Acknowledging that his determination will not settle the issue, the judge pointed out that the Minister has not ruled out the option of serving a stop notice in future.
His ruling is now set to come under further scrutiny when the case goes before the Court of Appeal.