Poland's Prime Minister Mateusz Morawiecki hosted the Dutch leader Mark Rutte for talks Monday about ways of stopping Russia's aggression on Ukraine and of helping Ukraine's fighters and civilians.

``We talked today about a blockade of all European ports to Russian ships and also on all sorts of sanctions, including on oil and gas,'' Morawiecki said.

Rutte said Putin has made a ``very big mistake'' by bringing war again to Europe.

``We will not accept this kind of aggression against a sovereign and democratic nation,'' Rutte said.

``And these are not empty words. We are showing we are willing to put out money where our mouth is,'' he said.

Morawiecki said they also discussed the gathering of evidence from the refugees of the ''really terrible, cruel crimes'' committed during the war in an effort to make sure that the crimes are punished.

More than 2.1 million refugees fleeing the war have come to Poland.

Unlike Poland and The Netherlands, Ukraine is not a member of the European Union. Poland backs giving it candidate status in a fast-track procedure.