Cuadrilla has halted its oil-drilling operations in West Sussex in anticipation of an influx of anti-fracking protesters at the site this weekend.

The company, which is pioneering the controversial process of hydraulic fracturing in Britain, said that after discussions with police it had doubled the height of its security fences and installed razor wire at the Balcombe site, and had called a halt to the drilling until further notice. A spokesman said this was owing to concerns "for the health and safety of employees and protesters".

Hundreds of people from the "No Dash For Gas" campaign group are expected on Saturday to join the scores of activists and local people already at the site.

No Dash For Gas is composed of protesters against fossil fuels from around the UK, who have demonstrated at power stations in the past. This year the group has decided to set up its annual camp at Balcombe to highlight opposition to fracking.

A Guardian poll this week found public opinion sharply divided on the issue of fracking: across the country, 44% of voters said they would support fracking in Britain, with 30% against and the rest undecided. But when asked whether they would welcome fracking in their local area, the proportion of supporters fell back to 40%, and the number opposed jumped to 40%.

Cuadrilla has said it has no immediate intention to frack at Balcombe, but is conducting exploratory drilling on an old oil well, abandoned by Conoco in the 1980s, to see if it can be made economically viable. If conventional drilling does not produce oil at the site, the company may apply in future for a fracking licence.

The past three weeks of protests have delayed drilling operations at the site but this is the first time exploration has been called off because of the threat of direct action.

The company's spokesman said: "After taking advice from Sussex Police, Cuadrilla is scaling back operations ahead of this weekend's No Dash For Gas event. During this time, our main concern is the safety of our staff, Balcombe's residents and the protesters following threats of direct action against the exploration site. We will resume full operations as soon as it is safe to do so."

Protesters outside the in Balcombe site said they were sceptical of the company's motives. "They are saying they are stopping, but it's just temporary so what does that mean?" asked one village resident, who preferred not to be named. "They are not going away. They are just waiting to see what happens." He said local residents were broadly supportive of the new wave of demonstrators poised to descend on the village, though some had reservations. "The people we've had here have been lovely, and have done a lot to raise the profile of what we are trying to do here."He said villagers were broadly supportive of the protesters.

On Thursday, Cuadrilla showed journalists a limited section of its Balcombe site, where about 30 workers are engaged in drilling exploratory wells. The site is slightly smaller than a football pitch in extent, and comprises one large rig that is drilling a hole about 13.5 inches wide, narrowing to 8.5 inches at the tip.

There is not much to see: the derrick that rises more than 20ft into the air is shorter than the crane brought in to heave into place new and stouter security barriers. There are several large containers of water, brought in from the surrounding area. Cuadrilla has drilled water wells on the site, but its purpose is to provide a baseline for the chemical composition of the water that can be used for comparison after drilling. The company said it had found there was methane occurring naturally in the water locally, but declined to say how much.

The drilling rig will be inactive while the protest intensifies. However, Cuadrilla officials noted that the exploration at the site had reached a natural pause in any case, with the current phase coming to an end while geologists analyse the samples of rock taken, to decide whether there is any point in drilling further.

Only about three workers remain on the site each night, and Cuadrilla has outsourced security for the site to G4S. On Thursday, there were at least 10 police vans present, and Sussex police has said about 70 officers have been regularly deployed at the site.

Even if oil can be produced there at economically viable rates, Cuadrilla has said this is unlikely to be the focus of their future operations in Sussex. Instead, the company will look for sites in the surrounding area, where it holds an exploration licence, but farther from the village. Any further drilling will require new permits from the planning authorities and Environment Agency, and require new exploration wells, and could involve both fracking and flaring if successful. Company spokesmen admitted this could take several years.

David Cameron weighed into the fracking row this week when he said this week that people must accept this new form of energy generation, despite widespread concerns.

Fracking is the process of blasting dense shale rocks with a high-pressure mixture of water, sand and chemicals. In the US, it In the US, fracking has been associated with water and air pollution. Proponents of the technology in Britain say these problems would be avoided as there are tighter regulations here.

Andrew Pendleton, head of campaigns at Friends of the Earth, said: "Cuadrilla's rhetoric is shifting fast in the face of overwhelming local opposition." Communities don't want to see their quality of life and local environment threatened by fracking, and are rightly sceptical about claims it will lead to cheaper fuel bills. The government should pull the plug on fracking and create an energy policy that generates jobs and tackles climate change by developing Britain's massive renewable energy potential."