MEPs in the eastern French city of Strasbourg declined to oppose the measure, which was backed by France and Germany.

There were 278 votes to stop it while 328 voted for a green light. There were 33 abstentions.

"I ask you not to reject this fragile, carefully negotiated compromise," Czech Prime Minister Petr Fiala, whose country has just taken over the rotating EU presidency from France, pleaded ahead of the vote.

The green label, known in EU parlance as the "taxonomy", "caters to a number of countries that will only be able to meet their climate targets as a result of these criteria," he warned.

A small but influential group of member states and activists had lobbied hard for MEPs to reject the green label, in a coalition of opponents to nuclear and gas energy.

Critics of gas point to the war in Ukraine as the latest reason to reject the green label, saying that encouraging investment would only increase dependence on Russian supply.

"How can we ask other countries to reduce their use of fossil fuels if we classify them as green? This will undermine the Paris agreement," said Dutch Green MEP Bas Eickhout.

Critics of nuclear energy point to the threat posed by accidents and nuclear waste and believe solar and wind energy is the best way forward.

But the EU executive, under pressure from nuclear-powered France and gas-reliant Germany, argues that both have a role to play as cleaner power sources during the transition to a net-zero carbon future.

The EU hopes that its label will steer huge sums of private capital into activities that support climate goals.