Demonstrators in the United States and elsewhere are protesting the natural gas drilling process known as fracking.

Participants in the "Global Frackdown" campaign rallied in cities and posted photos on social media websites over the weekend showing mostly small groups. But organizer Mark Schlosberg said he thought the protests went well and he pointed to photos showing larger demonstrations in South Africa and France as well as higher turnouts in cities in California, Colorado and New York.

Fracking has been a critical part of Oklahoma City based drillers development of oil and gas fields throughout the United States, and is now rapidly spreading to countries such as China and Argentina.

Scientists disagree on the risks of hydraulic fracking, a process that injects large volumes of water, sand and chemicals underground to break rock apart and free the natural gas. Federal and many state regulators say fracking can be done safely. But opponents say the process threatens public health and the environment.