Pushed by Germany and its powerful auto industry, the European Commission in December proposed walking back plans to ban sales of new petrol and diesel vehicles in 2035, to give carmakers more flexibility.

Instead, manufacturers would have to cut new vehicle exhaust emissions by 90 percent from 2021 levels -- and compensate for the remainder through various credit schemes.

But Germany's coalition government now wants to go further, according to media reports, by giving more room to hybrid vehicles.

In response, Denmark, Spain, France, Luxembourg, the Netherlands, Portugal and Sweden urged the bloc to stick with "a clear and ambitious pathway towards electrification."

"Undermining the integrity and predictability" of the bloc's rules on cutting automotive CO2 emissions "would be a strategic mistake," they warned in a joint letter ahead of a meeting of EU environment ministers later this month.

Citing the upheaval from the Middle East war, they said "the current energy crisis is a clear demonstration that reducing European dependence on fossil fuels is an absolute necessity."

"Electrification is not only a climate policy objective, but also necessary for our energy security," they wrote.

They also highlighted "uncertainties" surrounding the use of bio-fuels for road transport, a solution promoted by Italy, but which they suggested should be prioritised for the aviation and maritime sectors, where electrification can only play a limited role.

If Germany or Italy were to push to go beyond the European Commission's proposal, the seven countries would be able to form a blocking minority.

A French government official noted that the Mideast war had triggered a "rush" towards electric vehicles, calling it a "paradigm shift" that the EU needed to take into account.

"We're going to put things back in perspective a bit," said the official in the team of French ecological transition minister Monique Barbut, who initiated the joint letter.