Oil field near London's Gatwick airport is bigger than thought _ but will be hard to tap

A British energy company says an oil field near London's Gatwick Airport is much larger than previously thought, though experts warn it will be hard to tap.

UK Oil & Gas Investments PLC says research found as much as 158 million barrels per square mile in the Weald Basin in southern England, indicating it may hold more than 10 times as much oil as previously estimated.

CEO Stephen Sanderson says their holdings in the basin offer a "possible world class potential resource."

But Imperial College Professor Alastair Fraser warned the area's geology is "rather unfriendly," and while oil may exist, it will be difficult to get out of the ground.

The British Geological Survey had estimated the basin contains as much as 8.6 billion barrels of oil.