Signed in 1994, the ECT was designed to promote international investment in the energy sector, historically providing protections for investors in fossil fuels through investor-state dispute settlement (ISDS) processes.

Proposals to modernise the ECT better to support cleaner technologies have been subject to months of talks between European countries, resulting in a stalemate.

The UK joins nine EU member states — Denmark, France, Germany, Luxembourg, the Netherlands, Poland, Portugal, Slovenia and Spain — in withdrawing from the treaty. Ireland remains a member.

Graham Stuart, the UK’s minister of state for energy security and net zero, said: “The Energy Charter Treaty is outdated and in urgent need of reform but talks have stalled and sensible renewal looks increasingly unlikely.

“Remaining a member would not support our transition to cleaner, cheaper energy, and could even penalise us for our world-leading efforts to deliver net zero.

“With £30 billion invested in the energy sector just since September, we continue to lead the world in cutting emissions, attracting international investment and providing the strongest legal protections for those who invest here.”

Shaun Spiers, executive director of the Green Alliance, said: “Civil society organisations and parliamentarians from all political parties have been clear that the Energy Charter Treaty is an out-of-date agreement and undermines our efforts to tackle climate change.

“We welcome the UK’s decision to leave, which will strengthen global efforts to roll out cheap, clean renewable energy.”