North Lanarkshire councillors have been told any attempt to appeal a court ruling over Shore Energy's plan for Coatbridge is likely to fail.
The council could also be hit with legal costs "in the region" of £150,000, which would include the legal bills of Shore Energy and the Scottish Government.
The warning came from June Murray, head of legal services at the council, which has already tried and failed to overturn a decision by the Government to approve the plant.
Shore Energy is owned by butcher Simon Howie and he wants to build and operate the plant on the site of a former waste transfer station once operated by Shanks McEwan.
The landfill site is next to a school and houses near Carnbroe and close to the busy A8.
Thousands of residents, with the backing of councillors, have been campaigning against the proposed development.
The council took the battle to the Court of Session in an attempt to overturn the decision by the Government, only to be told there were "no legal grounds" to object.
Its planning and transportation committee are due to meet today to decide whether to appeal the ruling.
But Ms Murray said: "The views of senior counsel have been taken and, while it has been concluded that there may be stateable grounds on which to challenge the decision, the prospects of success are estimated as being slightly less than 50%."
She recommended in a report not to lodge an appeal. However, it is not clear if councillors will heed her advice. A council spokesman said: "We can't comment ahead of the committee meeting."
Mr Howie said: "In light of this unequivocal recommendation from its head of legal services, it is evident it would be reckless for the council to appeal."