French President Emmanuel Macron on Friday hinted at a fresh push to revamp the international taxation system to finance climate efforts.

Macron spoke on the sidelines of the Summit for a New Global Financing Pact in Paris, where delegates from across the world are discussing ways to reform the international financial system to help raise money for climate adaptation and mitigation efforts.

Top economists in France have been pushing for a new national wealth tax to finance the fight against climate change, spurring a debate inside Macron’s government.

But the French president dodged the issue at a press conference and in interviews Friday, instead suggesting measures such as a tax on financial transactions or an extra fee on airline tickets.