Climate activists are considering an appeal after the High Court in London on Tuesday dismissed a legal challenge to what they claimed was the UK government's "unlawful" financial support for North Sea oil and gas production.

The case was brought by three individuals — including a medical student and a former refinery worker — with the support of a coalition of green groups.

They were seeking a declaration from the court that the strategy governing the work of the Oil & Gas Authority (OGA), the North Sea regulator, which obliges operators to "maximise economic recovery" of UK oil and gas resources, was unlawful because it was calculated on a pre-tax basis.