The European Commission Wednesday requested a green light from EU governments to overhaul the bloc’s customs union with Turkey.

The customs union, in place since 1996, allows tariff-free trade of industrial goods between both partners but does not cover services, public procurement or agriculture, except from processed agricultural goods.

Modernizing the agreement “would bring substantial economic benefits for both partners,” the Commission said, noting that the 21-year-old accord “is becoming less and less equipped to deal with the modern day challenges of trade integration.”

The upgrade was agreed to at the 2015 EU-Turkey summit and is part of an agreement both sides struck in March to stem the flow of refugees coming from Turkey into the EU.

Under EU law, the Commission negotiates trade deals but needs a mandate from the member countries to do so. Diplomatic sources in Brussels said they expect the Commission’s request to be discussed in the Council’s Trade Policy Committee in January.

The customs union requires Turkey to open its market to products from all EU trading partners, but it gets no reciprocity for its own exports. If EU countries agree to follow the Commission’s plans, the upgrade of the customs union would expand mutual trade ties to agriculture, services and public procurement.