Hundreds of Romanian villagers opposed to fracking blocked Monday a convoy of vehicles intending to start test drilling for US energy giant Chevron.

Around 400 inhabitants of the eastern village of Pungesti, including many children and women, rallied on a nearby field where Chevron plans to start drilling its first exploration well.

The convoy was forced to turn around as protesters, some of whom had come in horse-drawn carts, called on Chevron to "go home".

Drilling for shale gas and oil has sparked controversy around the world due to concerns over the environmental impact of the technique used to free the hydrocarbons.

Hydraulic fraction or fracking pumps water and chemicals at high pressure into deep rock formations to free oil and gas, but environmentalists say the technique may contaminate ground water and even cause small earthquakes.

"We will not let them drill here if we must die for this," said one of the villagers, Gheorghe Hrum, a retired forest warden.

"They came with policemen and bodyguards to scare us but all we want is to be left alone, even if we are poor," he added.

The protesters also called on Prime Minister Victor Ponta to resign, accusing him going back on pledges to block shale gas drilling before he took power by granting Chevron exploration permits.

Chevron has permits prospect in three villages in this part of eastern Romania, and to explore for shale gas on Romania's Black Sea coast.

Chevron maintains that all its activities "have, and will continue to be conducted in compliance with Romanian laws, EU requirements and stringent industry standards."