Dozens of Greenpeace campaigners chained themselves to the gates of a shale gas exploration well in Pungesti in eastern Romania, the Reuters news agency reported Monday.

The activists also waved banners reading "Pungesti anti-Chevron quarantine area" and "Stop fracking!" in protest of the US energy giant's exploration work on the ground. They urged the leftist government in Romania to ban fracking altogether.

Chevron began work on the exploration well in Pungesti northeast of Bucharest in December last year after postponing operations there several times due to local opposition.

Huge potential, huge risks?

According to the US Energy Information Administration, Romania potentially holds enough shale gas to cover domestic demand for a century.

But fracking - the process which helps retrieve gas trapped in tight-layered underground rock formations by injecting water, sand and chemicals at high pressure - is not without environmental hazards, critics say.

They fear it can pollute ground water in the process and trigger small earthquakes.

US energy major Chevron has been the first company to begin exploring for shale gas in EU member state Romania and has said it aims to put up more wells in the area, while stating it will not yet use fracking under its five-year exploration program.

hg/cjc (Reuters, AP)