Finnish Finance Minister Alexander Stubb urged European Union members to keep their borders open and work together to tackle the region’s biggest influx of refugees since World War II.


“We should be looking for European solutions, not national solutions — and by this I mean we need more integration, not less integration,” Stubb said in an interview in Helsinki. “The inter-governmental methods that we are using — erecting walls, closing borders, refusing to share the burden, refusing to increase funding — lead to sub-optimal results.”


Stubb’s appeal comes against the backdrop of Sweden, Denmark and other EU countries reinstating border controls and German Finance Minister Wolfgang Schaeuble warning that the passport-free movement of people and goods throughout the region — known as the Schengen area — is on the verge of collapse.


Stubb joined Germany, which took in more than 1 million migrants last year, in calling instead for tighter controls on the EU’s outer frontier. That would include setting up locations outside the region to screen refugees before they enter the 28-member bloc and a common list of secure states to which asylum seekers can be returned.


Efforts thus far to reach a region-wide solution have failed as member states bicker over who should take responsibility for those fleeing war and poverty, and who should shoulder the costs.


“This is probably one of the biggest challenges of my political generation — hands down,” the Finance Minister said. “We need to defend basic European values.”


While calling for closer European ties as a whole, Stubb said that the United Kingdom should be allowed to opt out of deeper integration within the EU as the country prepares for a referendum as soon as this June on whether to remain in the bloc.


“If they don’t want to be a part of it, I think that should be allowed,” he said. “The U.K. has been a bit of a reluctant bride ever since its membership in 1973, and it’s good to settle that membership once and for all.”