Fracking company Celtique Energie presented data that hugely underplayed the number of heavy lorries needed for its planned drilling operations in Sussex, according to local highway officials. Other experts for the South Downs national park, in which Celtique plans to drill, said the company’s claims about noise were “opaque” and underestimated the increase in noise levels.

Celtique denies submitting misleading environmental statements. But it has sought to delay meetings at which its planning applications are decided while revised statements are put forward. If the delay is not granted, the company has said it will withdraw and re-submit the application, which would drive up planning costs. Ministers have repeatedly stated that the UK has “the most robust regulatory regime in the world for shale gas”.

As part of its planning application, Celtique claimed heavy goods vehicle (HGV) traffic would increase by 11-13% at its Widsborough Green site, but highway officials from West Sussex council concluded the actual increase would be 50-64%. The council made a similar objection about Celtique’s nearby Fernhurst site, with officials concluding the traffic assessment was not “a realistic or accurate representation”.

“It beggars belief and it is very concerning,” said Marcus Adams, who lives a few hundred metres from the Fernhurst site. “If Celtique can’t even do a traffic survey properly how can they drill safely? The government says we have gold-plated regulation for fracking, but I don’t believe it.”

Simon Clydesdale, an energy campaigner at Greenpeace, said: “The pollution and disruption from industrial lorries clogging up small country lanes is one of people’s main concerns about the impact of fracking. This is an area where energy firms should be scrupulously upfront and transparent with local communities. This is a major blow to Celtique’s credibility and their efforts to win the trust of local people.”

A company spokesman said: “Celtique have been very careful not to be misleading. We believe we have been overly cautious in our environmental statements and presented the ‘worst case’ in all areas. Our reputation is important to us as a responsible operator. We are confident this will all be demonstrated soon.”

In September 2013, the chief executive of Celtique, Geoff Davies, said: “We recognise that the vehicle movements associated with the proposals has been a key issue for many.” He said the environmental statements submitted at that time were “comprehensive”. However, the company now says it will submit a new traffic analysis shortly. “Celtique are currently preparing a response to these objections and are confident that the points raised can be adequately addressed in our response,” the spokesman said.

The planning decision meeting for the proposed Widsborough Green well is due to take place on Tuesday, unless Celtique’s request for a delay until September is granted. The main objection raised by West Sussex highways officials centred on the fact that Celtique’s baseline traffic survey had counted any vehicle over 1.5 tonnes as a heavy goods vehicle, despite the official Design Manual for Roads and Bridges giving 3.5 tonnes as the minimum weight of an HGV. “[Celtique’s] interpretation and conclusions included 4x4 vehicles, such as a Range Rover, as HGVs which serves to inflate ‘baseline’ figures for existing HGV movements,” the officials said.

The planning decision for Fernhurst was due on 10 July, but has already been delayed to September after West Sussex highway officials made a similar objection. The Fernhurst site lies in the South Downs national park and its governing authority commissioned an expert analysis of Celtique’s environmental statement.

The report concluded: “We have concerns regarding the adequacy of the groundwater and noise assessments and do not believe that these are sufficiently robust to allow the impact to be assessed with an appropriate level of rigour.” The report’s authors said the noise impact calculations were “opaque and not reproducible” and that their own calculations suggested noise “levels exceed the adopted limit, suggesting that those reported in the environmental statement may be underestimates.”

In May, Celtique abandonded plans to drill horizontally out from its Fernhurst site and under other people’s land, but still plans to drill vertical wells.

• Update: On 22 July, West Sussex council's planning committee rejected the application from fracking firm Celtique to explore at the Wisborough Green site.

“The shale industry’s clumsy attempt to impose fracking on Sussex has fallen at the first hurdle," said Greenpeace's Simon Clydesdale. "Celtique’s bid was in trouble the moment they were caught underplaying the impact of extra heavy freight needed at the site. Local councillors have set an example of rigour and independence for other local authorities to follow.”

