Children wait in front of a bus heading to Belgrade from the southern Serbian town of Presevo on September 11, 2015.

Germany’s Foreign Minister Frank-Walter Steinmeier urged central European countries on Friday to agree to a fair way to redistribute the rising wave of refugees hitting Europe’s shores, saying one country alone cannot solve the crisis.

The German minister met in Prague with his counterparts from the countries that most strongly oppose introducing mandatory redistribution quotas to deal with the influx.

Most migrants are trying to reach Germany and Steinmeier said an influx of about 40,000 refugees is seen this weekend.

“This challenge cannot be borne by one country. We have to invoke European solidarity,” he told a joint news conference with the foreign ministers of the Czech Republic, Slovakia, Hungary and Poland.

“I said to my colleagues that we have to agree on a fair mechanism of redistribution of migrants (still coming).”

The ministers said they agreed on several points in confronting Europe’s migrant crisis, including safe shelters, external border protection and the need for a list of safe countries to return migrants.

A plan unveiled this week by European Union chief executive Jean-Claude Juncker quadruples to 160,000 the number of refugees to be taken in, and sets mandatory quotas after countries earlier failed to offer to take in migrants on a voluntary basis.

Central and eastern European countries have made small voluntary contributions, with Hungary the exception, but would need to take several times more under the EU plan that would redistribute refugees entering Italy, Greece and Hungary.

The central European opposition has isolated the region and they may be outvoted on the plan. EU interior ministers are meeting on the issue on Monday.

While Poland has said it may take in more refugees than previously agreed, Hungary has said it made no sense to discuss quotas until Europe could protect its borders.

Hungarian Foreign Minister Peter Szijjarto said on Friday 180,000 migrants, many refugees from conflicts in the Middle East, have entered Hungary and that figure could rise to 400,000 to 500,000 by the end of the year.

Czech Foreign Minister Lubomir Zaoralek reiterated opposition to quotas after the meeting and said countries need to be able to keep national control over who they take in.

Slovak Foreign Minister Miroslav Lajcak said it was legitimate to question the quota system given that most migrants want only to use Slovakia and neighbours as transit countries on their way to the richer western Europe.

“It would be unfair if we raised our hands for some figure knowing that within two weeks these people will not be in Slovakia,” Lajcak said.

While Slovak Prime Minister Robert Fico has said Slovakia would prefer Christian refugees who can easily integrate in the country, Lajcak said religion or ethnicity would not be considered in taking in asylum seekers.