GENEVA: The United Nations said on Friday it could see no easing of the flow of refugees into Europe, with 8,000 arrivals daily, and that problems now facing governments may turn out to be only "the tip of the iceberg".

Hungary, which lies in the path of the largest migration wave Europe has seen since World War Two, said it was seeking support to halt an influx from Croatia after sealing its border with Serbia by building a 3.5-metre-high steel fence.

Amin Awad, regional refugee coordinator for the UN refugee agency UNHCR, told journalists in Geneva the body's past warnings on the scale of the problem had not been taken seriously.

"I don’t see it abating, I don’t see it stopping. If anything, it gives an indication perhaps that this is the tip of the iceberg."

Dominik Bartsch, the UN's deputy humanitarian coordinator in Iraq, said 10 million people were expected to need humanitarian support by the end of the year in that country, where 3.2 million were already displaced.

He said the United Nations was planning for the displacement of 500,000 people from the Iraqi city of Mosul if Iraqi forces launch an attempt to recapture it from Islamic State.

EU leaders have pledged at least 1 billion euros ($1.1 billion) for Syrian refugees in the Middle East and closer cooperation to stem migrant flows into Europe at a summit described as less tense than feared after weeks of feuding.

The greater number of asylum seekers reaching Europe, many on flimsy dinghies crossing the Mediterranean or on hazardous journeys hidden in trucks, are from Syria or Iraq. Others are from Afghanistan, Pakistan and African countries including Sudan, Eritrea and Somalia.

HUNGARIAN BORDERS

The German interior ministry said around a third of asylum seekers arriving in Germany who claim to be from Syria were probably not actually from that country, though spokesman Tobias Plate added that there were no precise statistics.

The arrival of the refugees, many abandoning refugee camps in Turkey, Jordan or Lebanon after three years or more, has stirred sharp disagreement between countries on how to 'process' and accommodate them. While governments such as Germany have proven more welcoming, eastern European countries have resisted plans for quotas to disperse refugees.

Right-wing Hungarian Prime Minister Viktor Orban said in Vienna that after construction of a steel fence to stop refugees entering from Serbia, migrants were now entering via Greece and the Balkans from Croatia. That border must now also be secured.

The flow will continue, Orban said, adding that the main question was how it could be stopped on the Croatian border.

"This is the big question of the next few days and weeks, I am trying to seek supporters for this," Orban told a news conference after meeting Austrian Chancellor Werner Faymann.

For now, thousands of migrants arriving on the Croatian-Hungarian border are shipped every day to the Austrian border.

He said Hungary would make a decision about sealing off its border with Croatia only after consultations to gather support for the move.

Not all refugees enter via eastern Europe and the Mediterranean. In recent days, about 500 refugees per day have crossed the Finnish land border in Tornio, near the Arctic Circle, after a long journey through central Europe and Sweden.

Finnish media reported that demonstrators had thrown stones and launched fireworks at a bus full of asylum seekers arriving at a reception centre in Lahti in southern Finland, late on Thursday. Between 30 and 40 protesters, one in a white robe like those worn by the white supremacist Ku Klux Klan in the United States, waved the Finnish flag and shouted abuse at the bus.

"The Finnish government strongly condemns last night's racist protests against asylum seekers who had entered the country," the government said in a statement. "Violence or the threat of violence is always to be condemned."