Sixteen protesters were arrested on Friday as British police broke up a blockade against exploratory drilling by a fracking company in southern England.

Campaigners demonstrated for a second day against planned test drilling by British firm Cuadrilla, which specialises in hydraulic fracturing for shale gas, known as "fracking".

The rural site in Balcombe, West Sussex, has become a focus for campaigners against the controversial technique, who fear environmental effects including chemical contamination of fresh water resources.

Fracking involves using huge amounts of pressurised water mixed with chemicals to crack open shale -- sedimentary rock containing hydrocarbons -- to release natural gas.

Police said that about 60 people had gathered and used a tree to block workers' access to the site where drilling is due to start.

The protesters included a professional clown and a former topless model.

Five people were arrested for causing danger to road users and 11 for blocking access. All were arrested "peacefully", Sussex police said in a statement.

Cuadrilla says its exploratory drilling at the site will not include fracking, but locals believe the technique will be used if the tests produce positive results.

Britain's finance minister presented tax breaks for energy fracking companies a week ago to create the world's "most generous" regime for shale gas extraction.

George Osborne revealed plans to slash from 62 percent to 30 percent the tax on a proportion of production profits, in a bid to encourage shale exploration.

Fracking has yet to begin in Britain, but has led to a shale gas boom in the United States.

Osborne's Treasury ministry believes it could increase Britain's energy security, create thousands of jobs and boost tax revenues.