Finland on Thursday said it was considering imposing tariffs on Russia in the latest escalation of a dispute over wood imports that threatens to undermine Moscow’s international ambitions.

In its most aggressive step yet in a stand-off that could delay Russia’s bid for membership of the World Trade Organisation and a partnership deal with the European Union, Helsinki said it might offer state aid to its struggling paper industry and pay for it with charges on the tens of thousands of trucks that cross Finland into Russia every year.