Hungarian leader Viktor Orban has warned that immigrants will alter “Europe’s civilisation”, amid ongoing EU debate on the Mediterranean crisis.

“A modern day mass migration is taking place around the world that could change the face of Europe's civilisation … if that happens, that’s irreversible”, he said in Budapest on Tuesday (2 June) according to the MTI news agency.

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"There is no way back from a multicultural Europe. Neither to a Christian Europe, nor to a world of national cultures”, he added.

"If we make a mistake now, it will be forever”.

The remarks follow a series of provocative episodes.

In April, Orban's government drafted a popular questionnaire asking if “the mismanagement of the immigration question by Brussels may have something to do with increased terrorism”.

In January, in the aftermath of the Charlie Hebdo attacks in Paris, he told Hungarian TV: “We don't want to see significantly sized minorities with different cultural characteristics and backgrounds among us. We want to keep Hungary as Hungary”.

The tough line is, in part, an attempt to win votes from the far-right Jobbik party at home.

It comes amid European Commission proposals for member states to relocate asylum seekers and to take in more refugees in a logarithm linked to national GDP.

Orban, on Tuesday, spoke at an event organised by the Konrad Adenauer Stiftung, a German foundation linked to the centre-right EPP group, which counts him as a member.

The same day in Brussels, at a meeting with leaders of secular and humanist societies, Frans Timmermans, the commissoner behind the migrant allocation proposal, defended the idea.

“We want to offer answers to the Mediterranean crisis, but you can’t offer answers … unless you have an asylum policy that works, and unless you have border control that works, and, of course, European solidarity”, he said.

He took note that several EU states - including France, Germany, and Poland, as well as Hungary - have criticised the relocation plan.

But he added: “If they have answers to these questions, I’d be more than glad to hear them. But I haven’t seen them yet. So far, I haven’t seen much that’s better than what we proposed”.

He also said, on the cultural issue, that “freedom or religion and freedom of conscience is a pillar of our society”.

Pierre Galand, the head of the European Humanist Federation, a Brussels-based NGO, noted that “diversity can enrich” European society.

He paid heed to concerns over Islamic radicalisation.

But he added: “We in Europe have lost sight of the historical fact that we’re all migrants, since the very beginning of our continent”.

For his part, Antonio Tajani, a European Parliament vice-president from Italy and a former commissioner, said “Europe should become a space for dialogue among religions and cultures”.

He also urged European Muslims to become “ambassadors for tolerance” in Islamic countries in north Africa and the Middle East.