SAN JUAN – Environmentalists marched Sunday in San Juan to protest the 150-kilometer (93-mile) pipeline that Gov. Luis Fortuño’s administration wants to build in northern Puerto Rico.

No official figures have been released, but organizers said a few thousand people turned out to protest one of the key projects being promoted by Fortuño.

Protesters marched from the Puerto Rican Capitol to La Fortaleza, the seat of the government in Old San Juan.

Sunday’s march was organized by the Sierra Club’s branch in Puerto Rico, environmentalists from the Casa Pueblo organization and the Puerto Rican Association of Historians, or APH, one of the latest groups to take up the fight against the project, which critics contend threatens the island’s historic and archaeological resources.

The U.S. Army Corps of Engineers released a report in December that concluded that the pipeline would not harm the environment and provided the best way of transporting natural gas to power plants in northern Puerto Rico.

The project will allow Puerto Rico to generate 71 percent of its electricity from natural gas by December 2014, with 12 percent of power being generated with fuel oil and the rest from renewable sources, the island’s government says.