Spanish oil giant Wednesday said an oil reserve it has access to in central Argentina contains the equivalent of 27,800 billion barrels of petrol.

"Repsol YPF is raising its forecast of resources and reserves in the hydrocarbon find in the Vaca Muerta formation to the equivalent of 22,807 billion barrels of petrol," it said in a statement.

It said the estimate was based on a survey carried out by appraisers of the company Ryder Scott at the reserve, which stretches for 30,000 square kilometres (11,500 square miles) in total.

Repsol said that development of part of the oilfield could increase Argentina's oil production by half.

Argentina produced an average of 580,000 barrels of oil a day in November, according to the latest monthly figures from the International Energy Agency.