Plans to drill for oil on the South Downs have been accepted, prompting environmental fears.

The decision by West Sussex County Council to allow Northern Petroleum (GB) to explore untapped oil resources in ancient woodland has been condemned by environmentalists.

Conservation charity The Woodland Trust called the proposal an "act of vandalism on our natural heritage".

Trust spokeswoman Alice Farr said: "This could only be the start of continued destruction of this ancient site and the surrounding area of outstanding natural beauty. If we continue to disregard our green spaces there will come a time when we have none left for future generations."

The council approved the application to temporarily tap into potential oil reserves yesterday afternoon. Northern Petroleum (GB) applied for consent to drill, test and, dependent on the findings, seek further permission for extraction or extended testing for oil.

The company plans to use a 36m-high drilling rig to search for oil at Markwell's Wood in the village of Forestside, near Chichester, over 19 weeks.

Its application was approved despite objections from Chichester District Council, the South Downs Joint Committee, the county council's landscape officer and ecologist.

The Wych Farm oil deposits along the South Downs are the largest onshore oil source in Britain and companies have been tapping the supply for the past 25 years.

County councillor for the area Mark Dunn said: "If the area really was ancient woodland I would oppose it. But I believe it is recently planted trees on a former ancient woodland. This scheme will give us a restored piece of woodland and an additional area when the reparation work is done.

"We care for the Downs hugely but we think we can make it better rather than worse.

"They are already drilling in Hampshire and near Singleton, and many people there are not even aware of it. I think there will be more drilling and, while we should look at alternatives, in the meantime we've got to husband all our resources."