Bulgaria, Romania and Serbia will be ready to close their borders to migrants if Germany and Austria do the same, Bulgarian Prime Minister Boyko said on Saturday.

“We won’t expose our countries to the devastating pressure of the millions [of people] who would come”, Borisov said after a meeting in Sofia with the Prime ministers of Serbia and Romania. “We won’t let our countries become buffer zones.”

“Huge waves of refugees go to our neighbours in Serbia via Greece and Macedonia.  If Germany, Austria and other countries close their borders, our three countries are standing ready to close ours in the same way.”

Borisov highlighted concerns over the “lack of a final strategic goal” in addressing the unprecedented migrant influx into Europe and called for support for EU’s recent agreement with Ankara to keep millions of refugees within Turkey’s borders.

“How far will this wave go, where will these refugees work, how will they be integrated, where will their children study?," Borisov said.

The three prime ministers met a day ahead of a planned meeting of European leaders on refugee flows along the Western Balkan route in Brussels on Sunday. The meeting was called by European Commission President Jean-Claude Juncker, who has been urging a coordinated response to the worst migration crisis in Europe since the end of World War Two.

Bulgaria, Romania and Serbia are among the countries which migrants and refugees cross on their journey from Turkey to northern Europe.

“The countries along the Western Balkans route have been particularly exposed to these pressures," Juncker said in a statement on Friday.

"I thank Prime Minister Boyko Borisov for the invitation, the date of today’s meeting has been chosen very well because we’ll discuss the issues in Brussels tomorrow,” Serbia’s Prime Minister Aleksandar Vucic said.

Serbia, Bulgaria and Romania must act together, in solidarity with Europe and demand solidarity from the other European countries to better manage the refugee crisis, Vucic said.

He added that Romanian Prime Minister Victor Ponta has offered help in enforcing controls along his country’s border with Serbia.

Sunday's summit in Brussels will bring together the leaders of non-EU Macedonia and Serbia plus eight EU countries: Austria, Bulgaria, Croatia, Germany, Greece, Hungary, Romania and Slovenia.