Donald Trump
Republican presidential candidate Donald Trump speaks to the crowd at town hall meeting Saturday, December 12, 2015 in Aiken, South Carolina. The South Carolina Republican primary is scheduled for February 20, 2016.Sean Rayford/Getty Images

Those who refuse to accept Syrian refugees are the "best allies" of Islamic State, the UN refugee chief said in an attack on the anti-immigration rhetoric of US presidential candidate Donald Trump and a number of European politicians.

UN High Commissioner for refugees Antonio Guterres told the Security Council that the 4.3 million Syrians who have fled the country's brutal conflict cannot be blamed for the terror they are escaping.

"Those that reject Syrian refugees, and especially if they are Muslim, are the best allies of the propaganda and the recruitment of extremist groups," Guterres said, as quoted by Reuters.

Two of the Isis terrorists responsible for the 13 November terror attacks in Paris were found to have entered the European Union posing as refugees. In response, anti-immigration groups such as Pegida in Germany and the Front National party in France have surged in popularity, and politicians in the US and Europe have warned of the danger posed by admitting refugees without first conducting strict security checks.

In the US, several states have said they will refuse entry to Syrian refugees, while Trump called for all Muslims to be refused entry to the US.

"We must not forget that - despite the rhetoric we are hearing these days - refugees are the first victims of such terror, not its source," Guterres said. "They cannot be blamed for a threat which they're risking their lives to escape."

He said that in a survey of 1,200 refugees to have entered Europe, 86% were found to have a secondary school education, while almost half had a university education.

"Syria is experiencing a massive brain drain," said Guterres. "One can only imagine the disastrous consequences of such an exodus on the future post-conflict reconstruction of Syria."

Democrat Presidential candidate Hilary Clinton has also claimed that Trump's anti-Muslim rhetoric was inadvertently helping Isis, with Trump calling on Clinton to apologise.

The International Organisation for Migration said on Tuesday, 22 December, that one million refugees had entered Europe in 2015, in the biggest wave of mass migration in the continent since the Second World War.