ExxonMobil is suing the EU in a bid to force it to scrap the bloc’s new windfall tax on oil groups, arguing Brussels exceeded its legal authority by imposing the levy. The lawsuit is the most significant response yet against the tax from the oil industry, which has been targeted by western governments amid a surge in energy prices following Russia’s invasion of Ukraine. The action threatens the viability of a levy the European Commission said would raise €25bn “to help bring down energy bills”. Exxon said the lawsuit was filed on Wednesday by its German and Dutch subsidiaries at the European General Court in Luxembourg City. It challenges the Council of the EU’s legal authority to impose the new tax — a power historically reserved for sovereign countries — and its use of emergency powers to secure member states’ approval for the measure.

Casey Norton, a spokesperson for Exxon, said the US supermajor recognised high energy costs were “weighing heavily on families and businesses” but argued the levy was “counterproductive” and would “undermine investor confidence, discourage investment and increase reliance on imported energy”.

Exxon had spent $3bn on European refining projects in the past 10 years, increasing output “at a time when Europe struggles to reduce its energy imports from Russia”, Norton said.

Exxon was now considering “future multibillion-euro investments” in the continent, Norton added. “Whether we invest here primarily depends on how attractive and globally competitive Europe will be.”

The so-called solidarity contribution was one of several measures agreed by the council in September to ease the burden on energy consumers, with the money raised to be recycled to hard-hit consumers or invested in clean energy supply.

Other measures included a cap on revenue from low-cost power generation. Exxon was not opposing these, Norton said.

The European General Court will decide whether to rule on Exxon’s lawsuit. If it does, any future judgment may be appealed at the European Court of Justice. Proceedings could drag on through much of next year.