Caudrilla Resources's site in the village of Balcombe in rural West Sussex has become a focal point for protesters who oppose fracking, a technique the company has pioneered in the search for shale gas in Britain.

Public debate on shale gas and fracking has intensified in recent months. 

The government in July proposed tax breaks for shale gas investment as part of its efforts to follow the United States, where surging production has lowered energy prices and cut imports.

Prime Minister David Cameron on Monday gave his unequivocal support to fracking, risking angering his party's supporters from more rural areas where any exploration is likely to take place. 

Hydraulic fracturing, or fracking, retrieves gas and oil trapped in tight-layered rock formations by injecting high-pressure water, sand and chemicals.

Critics say it can trigger small earthquakes and pollute the water supply, while others oppose any oil and gas exploration in picturesque parts of the countryside.