Denmark, which holds the rotating EU presidency, said it was working for an agreement "before the end of the year", after diplomats for several states called for talks on the target to be pushed back.

The European Commission has announced plans for the 27-country union to cut emissions by 90 percent by 2040, compared to 1990 levels.

A key milestone towards the EU's goal of becoming carbon neutral by 2050, the target needs approval from the European Parliament and member states.

But this has not been forthcoming.

A commission pledge to create some wiggle room by allowing countries to count carbon credits purchased to finance projects outside Europe has failed to persuade hardliners like the Czech Republic and Hungary, which think the goal is too ambitious.

Wopke Hoekstra, the European Commissioner for Climate, told AFP on Tuesday that there was a "significant possibility" a deal would be finalised at a meeting of EU environment ministers next week.

But that prospect faded Friday as several countries, said to include France, Italy, Germany and Poland, asked that the matter be discussed at an October leaders' summit before any decision.

"Climate ministers will meet on September 18 to have a policy debate on the climate law with the aim to stabilise the text," the Danish presidency of the European Council of member states said.

The delay could jeopardise the commission's hopes to have the 2040 objective approved before the UN climate conference (COP30) in the northern Brazilian city of Belem, which starts on November 10.

The nearly 200 countries under the Paris Agreement are supposed to put forward updated policies providing a tougher 2035 emissions reduction target and a detailed blueprint for achieving it before COP30.

The EU's 2040 plans should inform the bloc's 2035 submission, but some countries including France are pushing for the two to be treated separately, a position criticised by climate groups worried that the bloc risks abdicating its leading global role on climate issues.