The chief executive of Cuadrilla, a leading fracking company, has complained at what he calls intimidation and harassment by “irresponsible” activists protesting at a shale gas site the firm is constructing in Lancashire.

The CEO, Francis Egan, said he felt the balance between the right to protest and the right for companies to go about their business had tipped in the wrong direction.

Work began in January on the company’s Preston New Road site, in Little Plumpton, Fylde West. It will be the location of the UK’s first horizontally fracked wells.

Each day, 10 to 20 people have protested outside the site’s fence. The majority were peaceful, and most of the aggressive protest was people shouting through the fence, Egan said. However, Cuadrilla said one worker leaving the site had the windscreen of his van smashed by an activist wielding a chain. The employee had refused to go back to the site.

Demonstrators last week at Preston New Road. Photograph: Ashley Cooper/Barcroft Images

“There’s verbal abuse,” said Egan, about the protesters. “They swear at people. One guy [a Cuadrilla worker] had a death threat which he reported to police. You don’t think someone’s going to follow it through, but it’s indicative of how strongly they’re feeling. They shout things like ‘you mustn’t have children because you wouldn’t do this if you had children’, ‘how can you live with yourself’.”

Two suppliers subcontracted to supply material for the site, one for stones and one for cement, have ended their relationship with Cuadrilla’s civil engineering contractor after protesters blockaded their businesses.

“In view of the drastic effect this is now having on the rest of my customers we have no alternative but to cease supplies to the above site [Preston New Road],” the cement company, Moore Readymix, wrote in an email to A E Yates, the company contracted to do the site works.

Egan said of the protests and pressure on suppliers: “I think it is irresponsible because people have a right to go about their day to day work. Your right to protest shouldn’t be allowed to supersede some business’s right to do business with us.”

A Cuadrilla shale gas drilling rig at Weeton, Blackpool, Lancashire. Photograph: FLPA/Alamy

Cuadrilla also said that activists wearing hi-viz jackets were stopping and waving over lorries on the A-road by the site and asking the drivers where they were going. Lancashire police said there had been about 30 arrests relating to incidents near the Cuadrilla site since the start of January, for a variety of offences, including obstructing the highway.

Anti-fracking activists this week vowed to continue persuading Cuadrilla’s suppliers to drop contracts, starting with a series of direct actions from 27 March.

Ash Hewitson, of the group Reclaim the Power, said: “By taking out the links in the chain we can break the whole industry into pieces.”

Egan questioned whether it was right that the firm should be threatened in such a way. “We’re not doing anything illegal, immoral. I believe we’re doing something useful. You may have a different view. Fine, express it, write to your MP, come and shout – we’ve provided a protest area. You can scream, shout, wave banners, but don’t try and stop someone doing business with us.”

Campaigners said the company was trying to depict them unfairly, and complained at what they said was a disproportionately large police presence.

Barbara Richardson, a retired teaching assistant who lives at the nearby village of Roseacre, said she had been outside the site most days since the work began. Protests had been peaceful and relations cordial with the police, she said. “Cuadrilla are out to exaggerate and make protesters out to be far more aggressive than they are,” she said.

Richardson said the policing had become more heavy handed after anti-fracking activists locked themselves together in January and February. “Yesterday there were six police vans, and every time a van came [to and from the site], 50 officers came out to surround them.” On Wednesday, local police apologised for how they had characterised an anti-fracking rally last weekend.

Another fracking company was embroiled this week in a war of words with protesters. John Dewar, director of operations at Third Energy, which is fracking a well in Kirby Misperton, North Yorkshire, said to activists: “Please go away. We respect their right to protest but they should respect our right to operate.”

Robert Laycock, a resident in the district, said in response: “Our holiday cottage business, Flamingoland, Castle Howard and all the other tourist businesses in this area, will all be affected by that [fracking]. He says ‘please go away’ – we are not going to go away, we live here.”