Ineos Shale has verbally ramped up its fight with the UK’s National Trust, the charity that runs the historic Clumber Park in Nottinghamshire, where the company wants to conduct seismic surveys and explore the potential for fracking.

The UK subsidiary of the Swiss-based olefins and polyolefins group is now threatening to seek to force the Trust – which up to now has refused all of its advances – to grant it access to the land. The company said earlier it might invoke the Working Facilities and Support Act of 1966 if landowners refuse permission to survey. This law dating from the coal mining era would allow would-be drillers to apply for an “ancillary right” of access.

Ineos noted that it has already received permission from nearby landowners to drill wells – a process it says is geologically “non-invasive” – and its ability to extract gas would be "significantly limited" if it cannot access Clumber Park.

If the National Trust refuses to change its position, Ineos said it will have “no choice” but to write to the UK Oil and Gas Authority, asking for permission to seek a court order enforcing its rights to carry out the surveys. In February, it said “large tracts of land such as Clumber Park can be dealt with separately to the rest of the survey and any action we decide to take under the act will not hold up the main survey.”

The company has won a number of government licenses to explore fracking potential in the English Midlands as well as in Scotland, which it said give it “a legal obligation” to investigate shale gas deposits. It criticized the charity's position as "overtly political."

In a statement to UK media, the National Trust reiterated its opposition to fracking and said it will continue to reject all related requests or inquiries, which would also extend to surveying for fracking purposes. “The fossil gas that fracking releases is a finite resource: non-renewable, its combustion produces greenhouse gases which contribute to climate change,” the charity said.