PARIS — France's constitutional council has upheld a law banning fracking in France, keeping in place a law that had been a centerpiece of Socialist President Francois Hollande's campaign.

Activists say fracking, also known as hydraulic fracturing, is disastrous for the environment, spewing dirty water, fouling the air, and sickening people and animals. France banned the practice in 2011 over the objections of the oil industry.

Fracking — sending a pressurized mix of water, sand, and chemicals into shale to release the gas — has changed the energy landscape.

Its use in the United States upended energy markets and led to wholesale prices for Americans that are about a third of what customers in Europe pay.

European Union lawmakers on Wednesday voted to require environmental studies from companies that want to use fracking.