An oil company has been successful in drilling for oil in an area of ancient woodland.
Northern Petroleum said it will carry out further tests in Markwells Wood, near Chichester, West Sussex, to determine the site's potential.
It plans to drill to 1,380m (4,528ft) and believes it could yield between 35 million and 61 million barrels of oil.
West Sussex County Council granted the company permission to search for oil in 2008.
But environmental campaigners are concerned about the damage the drilling could cause to the area, which is part of the South Downs National Park.
A spokeswoman for the South Downs Society said: "It is going to be a fairly small drill, however there will be destruction of vegetation.
"There will also be noise pollution from the sound of the heavy machinery so it will stop people from being able to have a quiet walk in the woods.
"We objected to the original application in 2008 and continue to maintain our view that drilling for oil in a national park is not the right place to be doing it."
Northern Petroleum managing director Derek Musgrove said: "The Markwells Wood-1 well has to date presented us with encouraging results.
"Success at Markwells Wood, helped by current oil prices, should enhance the value of the other undeveloped discoveries and exploration prospects held under licence by Northern in the UK."