Justice Mira Dean-Armorer's ruling late Tuesday is in response to a complaint that the Environmental Management Authority did not follow procedure when it gave permission to the state-owned company Alutrint to move forward on a $786 million project including the smelter, an electricity-generating plant and a seaport from which the commodity would be exported.

"Outrageous, irrational and procedurally irregular," Dean-Armorer wrote of the agency's decision to award the company a certificate of environmental clearance.

The judge also said that the agency did not publicize a report _ as is customary _ on the cumulative effect that the plant would have on the area.

Environmental Management Authority director Joth Singh said Wednesday that the government would probably appeal the ruling.

Prime Minister Patrick Manning said his administration still plans to complete the project.

"We are analyzing exactly what took place in the High Court last night" before deciding how to proceed, he said.

The smelter, a joint venture between Alutrint and Venezuelan company Sural, was expected to start operating in 2011. It would be located in the southern coastal area of La Brea.

Until now, work has begun only on the electricity-generating plant.