European Council President Donald Tusk addresses a joint press conference with Maltese Prime Minister Joseph Muscat and President Macky Sall of Senegal at the end of the Valletta Summit on Migration in Valletta, Malta, November 12, 2015. [Photo/Agencies]

VALLETTA -- European Council President Donald Tusk said on Thursday the Schengen treaty, which allows free movement, was under threat and that time was running out.

Speaking at the end of an informal European Union (EU) summit in Valletta, the former Polish official said: "We need to regain control of the external border as a precondition for European migration policy."

He highlighted the EU would respect its obligations to migrants, but without registration there were no rights. Furthermore, asylum seekers could not decide where they would be given asylum.

EU leaders reiterated their concerns about the Schengen agreement as Sweden reintroduced border controls and Slovenia built razor-wire fence.

Asked what needed to be done to protect the Schengen agreement, Tusk said there needed to be effective implementation of the rules, but he understood that the Dublin rules were unfavorable to some countries in the current influx of migrants.

Tusk added the summit had focused on relations with Turkey and it was agreed to hold a summit of the EU 28 with Turkey as soon as possible. He was confident of a mutually beneficial relationship.