UPM will contribute assets in Germany, Finland, Britain and the United States to the joint venture while Sappi's contribution will come from assets in Austria, Germany, the Netherlands and Finland.
The deal comes amid falling demand in the industry due in part to digitalisation, structural overcapacity, high energy costs and rising paper imports from Asia and Latin America.
The Commission, which acts as the EU competition enforcer, can clear the deal with or without demanding concessions after its preliminary review or it can open a full-scale investigation subsequently if it has serious concerns.