London, April 9 (IANS): A "significant" oil find has been made in Britain, with a British oil exploration firm saying that up to 100 billion barrels of onshore oil could be lying beneath southern England.

The firm UK Oil & Gas Investments (UKOG) drilled a well at Horse Hill, near Gatwick airport last year, and analysis of that well suggests that the area could hold 158 million barrels of oil per square mile, BBC reported on Thursday.

However, UKOG admitted that only a fraction of the total reserve of 100 billion barrels of oil would be recovered.

The North Sea has produced about 45 billion barrels in 40 years.

"We think we've found a very significant discovery here, probably the largest (onshore in Britain) in the last 30 years, and we think it has national significance," Stephen Sanderson, UKOG's chief executive, told the BBC.

UKOG said that the majority of the oil lay within the Upper Jurassic Kimmeridge formation at a depth of 2,500 feet to 3,000 feet.

It described this as a "world class potential resource" and said that the well had the "potential for significant daily oil production".

Compared with similar geology in the US and West Siberia, UKOG estimated that 3 to 15 percent of the oil could be recovered.

Oil has been produced onshore in southern England for decades. There are currently around a dozen oil production sites across the Weald, a region spanning Kent, Sussex, Surrey and Hampshire counties.

Last year, a report for the government by the British Geological Survey estimated that the region may have shale oil resources in the range of 2.2 to 8.5 billion barrels, with a central estimate of 4.4 billion barrels of oil.

UKOG said that it drilled the deepest well in the region in the last 30 years and that the results "comprehensively change the understanding of the area's potential oil resources".

"Based on what we've found here, we're looking at between 50 and 100 billion barrels of oil in place in the ground," said Sanderson.