BRUSSELS (Reuters) - A top European Union official urged member states on Tuesday to back the United Nation’s migration pact amid a growing tide of dropouts that highlight how Europe has turned colder on accepting foreigners.

At least six EU states have already shunned the accord to regulate the treatment of migrants worldwide, a sign of how the bloc has turned increasingly restrictive on accepting refugees and migrants alike since a 2015 spike in arrivals.

“I make a last call on them to rethink and reconsider their position,” the EU’s Migration Commissioner Dimitris Avramopoulos told a news conference.

The Global Compact for Safe, Orderly and Regular Migration was agreed in July by all U.N. member nations, except the United States. The voluntary pact is due to be formally adopted in Marrakesh on Dec. 10-11.

It was conceived after the biggest influx of people into Europe since World War Two, many fleeing conflicts and poverty in the Middle East and Africa. Sea arrivals have since dropped sharply but political aftershocks still reverberate in the EU.

Some former communist east bloc states - the Czech Republic, Bulgaria, Hungary, Poland and Slovakia - have renounced the U.N. agreement.

The issue has led to a government crisis in Belgium where the liberal premier wants to sign but the right-wing N-VA party threatens to bring down the ruling coalition if he does.

Austria has said it will not sign up and opposition from Italy’s prominent interior minister, the right-wing Matteo Salvini, has thrown Rome’s support into doubt.

In the Netherlands, a recent opinion poll showed 41 percent of people against signing the pact versus 34 percent in favor. Outside of the EU, Australia has also quit.