The Europe's competition supremo Margrethe Vestager has said reforming EU competition law is a major priority for Brussels and could help accelerate the bloc's ambitious Green Deal.

"I have learned never to give a date because otherwise everyone focuses on respecting the timetable and not on the quality of the work," Vestager told AFP in an interview on Wednesday.

"We are reviewing our state aid rules to see if they are compatible with the Green pact," the Danish commissioner said.

On Tuesday it formally launched a trillion euro ($1.1 trillion) plan to finance its goal.

But the plan -- which commits member states to build a carbon-neutral economy by 2050 -- risks colliding with the EU's strict rules on state aid.

Vestager's teams have the task of checking whether aid granted by an EU government to a company is compatible with competition law.

Given the ambition, observers believe that the commission could be more conciliatory about state aid if intended to finance so-called "green" projects that could help the transition towards renewables.