On a frozen field braving police, Romanian villagers hold vigil in a makeshift camp set up to block US energy giant Chevron from exploring for shale gas.

On Monday, hundreds of Romanian riot police forcibly removed protesters from the camp clearing the way for Chevron's excavators to reach the site where the company intends to drill its first exploration well in Romania.

But some of the villagers from Pungesti, in this impoverished region of North-Eastern Romania, hung on, taking turns to man the camp just adjacent to the Chevron site and despite an imposing police presence.

"We have potatoes to eat, an improvised stove. We protest to protect our way of life and our health," one of the local farmers, Alexandru Focsa, 44, told AFP.

"The authorities do not want to listen to us but we are determined to go on despite the abuses and the fines handed by the police," he said.

Like Focsa, many in this rural region oppose the highly controversial drilling technique used to extract shale gas known as "hydraulic fracturing" or "fracking".

Widely used in some US states like Pennsylvania and North Dakota, it has been banned in France and Bulgaria because of potential pollution to air and water.

Angered, locals have been organising sit-ins and protests since Chevron obtained three permits to drill in the hills around Pungesti earlier this year. Mass rallies also took place in Bucharest.

Their ire has especially turned on the centre-left government of Victor Ponta, who opposed shale gas while in the opposition but became a promoter once in power.

In October, protests in the village forced Chevron to postpone test drilling, but on Monday police were present to intervene.

"Police arrived at night, they beat us up with batons and dragged us away," Focsa told AFP though police said they used force only to clear a public road.

At dawn, an AFP photographer saw a riot police commander arrive at the makeshift camp and order a colleague to begin making arrests.

But when police learned journalists were also present, the arrests did not take place, and a government mediator asked only if protesters needed bread.

Greenpeace on Tuesday slammed the operation as "a serious abuse against the freedom of expression", reminding that the permits are currently being challenged in court.

Following the raid, Chevron said its priority was to "conduct its activities in a safe and environmentally responsible manner".

"We will continue our dialogue with the public, local communities and authorities," the company added.

Despite the protests, Chevron also said its exploration work was able to begin on Monday as planned.

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CHEVRON