There is no alternative to the Schengen regime in tackling the migrant crisis, European Council President Donald Tusk and Croatian Prime Minister Tihomir Oreskovic agreed at their meeting in Zagreb on Wednesday.
"There's no alternative to respecting the Schengen Code. Only the Schengen rules can be the basis of a comprehensive European solution," Tusk said at a joint press conference.
Tusk had arrived in Zagreb as part of a tour of the countries along the Balkan migrant route, ahead of a summit with Turkey and a European Council meeting in March at which a comprehensive European plan for the migrant crisis is expected to be adopted
European leaders are opposed to unilateral border restrictions on the Balkan route and want the influx of migrants to be stopped in Turkey and on the border between Turkey and Greece.
Oreskovic said that the Schengen rules should be observed and that Greece, which is taking the brunt of the refugee crisis, should be assisted as much as possible. He added that assistance should also be extended to Macedonia, where Croatia has already sent its police support.
Oreskovic said that the Croatian government would launch a procedure to amend the relevant law to make it possible for the army to help the police in guarding Croatia's borders in the event of a humanitarian need.
Restrictions on the flow of refugees and migrants, first introduced by Austria and then by other countries on the Balkan route, have resulted in chaos on the Greek-Macedonian border, with more than 20,000 refugees stranded there in cold weather.
Tusk said that Macedonia needed assistance in managing "a crisis that is testing our union to the limits" and causing tensions in the EU and the region.
"The EU understands the difficult situation of the authorities in Skopje. We cannot and we should not leave them alone in this situation," Tusk said, adding that the EU member states must be mobilised to help with the humanitarian crisis in Greece and other Balkan countries, he added.
Insisting on the Schengen regime, Tusk reiterated the earlier position of the European Council that the migrant crisis cannot be resolved by unilateral measures, but by stepping up the protection of the EU's external borders, establishing functioning refugee collection centres in Greece and sharing out the migrants and refugees among the EU members.
"We have to avoid an illusion that instead of full respect for the Schengen rules there might be another, even convenient European solution. Respecting the Schengen rules will not solve the migration crisis, but without Schengen we have no chance to resolve it," Tusk said.
He said that there was no alternative to cooperation with Ankara, stressing that the EU-Turkey action plan, under which Turkey committed to reducing the influx of migrants into European in exchange for financial assistance and political concessions, must be set into motion as soon as possible.
The EU-Turkey Summit is scheduled for March 7 and the European Council is due to meet on March 17 and 18.