France, Jan. 2 -- Importers of these goods must declare the carbon dioxide emissions embedded in their products. If those emissions exceed EU standards, they must pay a levy.

The policy, known as the Carbon Border Adjustment Mechanism (CBAM), is designed to ensure foreign producers face a carbon cost similar to that already paid by European companies under the EU's internal emissions trading system.

Some trading partners argue the measure restricts trade and favours European manufacturers. The EU says the system encourages cleaner production because countries can avoid the levy by imposing an equivalent carbon price on their own industries.

"Pricing carbon is something that we need to pursue with as many as possible, as quickly as poss...