A campaign group has asked for a judicial review of the decision to allow a multi-million pound chicken waste plant to be built near Glenavy.
The Communities Against the Lough Neagh Incinerator (CALNI) claims planning procedures were not properly followed.
The campaigners include the former vice-chancellor of Queen's University, Sir George Bain.
Environment minister Edwin Poots has said the plant represents the kind of investment needed in NI.
The group behind the proposal, Rose Energy, is a consortium of Moy Park, O'Kane Poultry and Glenfarm Holdings Limited.
It says it will power 25,000 homes by burning chicken waste and bone meal.
CALNI president Danny Moore said his group had written to the United Nations in Geneva citing Planning Service breaches of the Aarhus Convention.
The convention, agreed in 1998, guarantees the public the right to involvement in policymakers' decisions on environmental matters.
Mr Moore said that CALNI were pursuing the legal route because it had not been given sufficient access to the Planning Service file or to Planning Service consultees.
The group also wants a public inquiry.
"The minister's decision does not mark the end of the process, but only the end of the beginning," Mr Moore said.