Liese, a senior EU lawmaker in the influential European People's Party - the biggest lawmaker group in the European Parliament - said the group was still developing its position, but that he believed a 90% goal would overburden industries.

"Many of us, in particular, in Council and Parliament, we see the 90% as very ambitious, I even would say over-ambitious," he said in an interview.

"We really think when the 90% is implemented without any flexibility, then it will lead to de-industrialisation."

The European Commission is drafting a proposal for the EU's 2040 climate target and is exploring softening its goal from a previous plan to cut EU emissions by 90% to win over skeptical governments and lawmakers concerned about the cost for businesses, Reuters reported earlier on Monday.

Liese is the centre-right EPP group's most senior lawmaker on climate policies. The EPP holds 188 of 720 seats in the European Parliament, crucial to forming the parliamentary majority needed to approve the EU's 2040 climate goal.

The EU's independent climate science advisers have recommended a 90% to 95% emissions-cutting goal as achievable.

However, a topic that has shot up the EU's political agenda this year is helping European industries that are struggling amid cheaper imports and U.S. tariffs.

An overall 90% target which sets a lower emissions-cutting target for domestic industries and allows countries to buy international carbon credits to make up the rest "could be a way out," Liese said. He said the EU would need to ensure these credits have high environmental benefits.

Sources have told Reuters the Commission is looking into this option.

CO2 credits have faced multiple scandals where credit-generating projects were found to not deliver the climate benefits they claimed.

An 85% target would still be ambitious for 2040, Liese added.

Socialist and Green lawmakers support a 90% target, while right-wing lawmaker groups including the European Conservatives and Reformists have opposed it.