Balcombe oil drilling: Protesters block Cuadrilla truck
Up to 100 protesters blocked a lorry trying to enter a site where test drilling for oil is to take place.
The vehicle had its brake lines cut during the demonstration near Balcombe, Sussex, said Sussex Police.
Officers said the truck was quickly repaired without "interference from any demonstrators".
Cuadrilla plans to start drilling a 3,000ft (914m) vertical well and a 2,500ft (762m) horizontal bore to the south of the village on Saturday.
The company said it was a temporary operation and any further activity would need fresh permission.
'Not the solution'
Campaigners are also demonstrating over fears the tests will lead to a large increase in the number of lorries in the area and about Cuadrilla's involvement in shale gas exploration using hydraulic fracturing, or fracking.
Simon Medhurst, who locked himself into a tunnel under the Bexhill-to-Hastings link road in January, and Marina Pepper, former Playboy model and ex Liberal Democrat mayor of Telscombe, are among the activists.
They have pledged to mount a day-and-night campaign of resistance.
Many waved banners with anti-fracking and anti-fossil fuel slogans and sang songs while they blocked the lorry from going into the drilling site.
Brenda Pollack, regional campaigner for Friends of the Earth South East, said: "Shale gas and oil are not the solution to our energy challenges.
"They threaten local communities, pollute our atmosphere and there's plenty of evidence they won't bring down fuel prices.
"It's time to end the nation's costly addiction to dirty fossil fuels and build a clean future based on energy efficiency and harnessing the power of the wind, waves and sun."
'Oil drilling only'
The tests will see if oil or gas, if found, can be extracted.
Cuadrilla obtained a waste permit from the Environment Agency on Tuesday - the final regulatory approval it needed to carry out the work near Balcombe.
A spokesman for the energy firm said: "Cuadrilla's forthcoming activity at Balcombe is for exploratory drilling only and is a temporary operation that will not include hydraulic fracturing.
"Should Cuadrilla wish to undertake further activity, they would need to apply for new permissions and licences from the relevant regulatory authorities.
"We have communicated what we are doing to the local community through information sessions and written communications.
"Furthermore we have been in regular contact with the parish council and other local councils as well as going through all the necessary planning and permit applications to undertake this work."
West Sussex County Council granted Cuadrilla planning permission to undertake exploration work in 2010.