The United Nations hit back Monday at calls to turn back refugees from Syria to prevent extremists like those who carried out the Paris attacks from entering as purported asylum-seekers.

The UN comments came as European countries, Canada and the United States were facing calls to deny entry to refugees after French investigators said one of the Paris attackers was a Syrian national who may have slipped into Europe as part of a wave of migrants.

“It is understandable that countries need to take whatever measures they need to take to protect their own citizens against any forms of terrorism,” said UN spokesman Stephane Dujarric.

“But focusing that on refugees, vulnerable people who are themselves fleeing violence, would not be the right way to go,” he said.

“These are people who are fleeing the very destruction of Daesh that we have seen in Paris,” said Dujarric, using the Arabic name for the Islamic State (ISIS) which claimed responsibility for the attacks on Friday that left 129 dead.

France’s anti-immigration National Front leader Marine Le Pen called for an “immediate halt” to new arrivals, while Germany’s anti-Islamist PEGIDA movement slammed Europe’s immigration policy as a failure.

UN Secretary-General Ban Ki-moon has repeatedly said that closing borders is not the answer to Europe’s worst migrant crisis since World War II and encouraged governments to take in more refugees.

“The reaction to the wave of refugees we have seen should be one of compassion and empathy,” Dujarric said Monday.

There are fears some of the assailants entered Europe as part of the huge influx of people fleeing Syria’s war, after a Syrian passport was found near the body of one suicide bomber at the Stade de France in the name of Ahmad Al Mohammad.

The document has yet to be verified and Serbia detained a migrant on Monday whose passport contained the same data.

Meanwhile, the State Department in Washington indicated on Monday that the United States plans to go ahead with a program to accept 10,000 Syrian refugees despite calls by governors of 24 states to halt it.

AFP contributed to this report.