European Union leaders will gather for an emergency summit on the migration crisis on Wednesday, a day after ministers forced through a controversial deal to relocate 120,000 refugees in a major blow to unity within the bloc.

Interior ministers briskly voted through the deal Tuesday, under which EU countries must take a share of new arrivals from overstretched frontline states like Greece and Italy.

But in a rare step, it was passed by a majority vote instead of unanimously, with fierce opposition from eastern states.

Also READ: EU relocation plan voted in

Hungary, the Czech Republic, Romania and Slovakia all voted against the plan while Finland abstained, straining regional ties as Europe wrestles with its biggest migration crisis since World War II.

Luxembourg's Foreign Minister Jean Asselborn, whose country holds the rotating presidency of the EU, said the plan was forced through despite opposition because it was an "emergency situation".

"If we had not done this, Europe would have been even more divided," he told a press conference.

With the relocation vote out of the way, Wednesday's emergency EU summit will focus on strengthening the bloc's external borders, as well as giving extra funding to Turkey, Jordan, Lebanon and UN agencies.

But there may trouble ahead as Greece will likely face pressure to accept outside help in managing its borders -- renewing sovereignty concerns in Athens just months after it was forced to accept a huge eurozone bailout.

'The emperor is naked'

Europe is under increasing pressure over its handling of a huge influx of hundreds of thousand of migrants this year, many of them fleeing conflict and repression in Syria, Afghanistan and Eritrea.

"We have no choice but to leave," said Abdullah, a 35-year-old father-of-two from war-ravaged Aleppo in Syria who has worked for three years to save up the money to travel to Europe.

The EU's new relocation plans were outlined after pictures of a drowned Syrian refugee toddler lying on a Turkish beach sparked global outrage.

But the proposal has opened fresh rifts in a bloc already reeling from the Greek debt crisis.

Hungary and its eastern partners oppose the plan because they say Brussels has no right to make them take in thousands of people, and to do so amounts to a violation of their national sovereignty.

"Very soon we will find that the emperor is naked. Common sense has lost today!" Czech Interior Minister Milan Chovanec tweeted after the vote.

In Bratislava, Slovakian Prime Minister Robert Fico said he was prepared to break the EU's rules rather than accept the proposal.

"I would rather go to an infringement than to accept this diktat," he said, quoted by Slovakia's leading SME daily.

Ahead of Wednesday's meeting, US President Barack Obama pressed European nations to take their "fair share" of refugees.

The statement, which came after a phone call with German Chancellor Angela Merkel Tuesday, is likely to be seen as a warning to those who opposed the deal.

But his call will be diluted by accusations that Washington itself has not done enough to address the crisis, despite being the leading humanitarian donor to the region.

With millions of Syrians forced into camps across the Middle East, tens of thousands crossing Europe on foot and hundreds washing up dead on beaches, America has promised to take in only 10,000 as refugees next year -- a figure dwarfed by the up to one million Syrian refugees Germany is expecting to take in this year alone.

'Hotspots'

The crisis has raised fears the EU's cherished Schengen passport-free zone could collapse as countries close their borders to stem the flow of migrants, many of whom are heading for Germany.

Officials said the relocation deal covered 66,000 refugees who would be moved from Greece and Italy to other EU countries, plus another 54,000 who had previously been earmarked to be relocated from Hungary before it refused to back the plan.

It also involves the creation of "hotspots" -- special centres in frontline states for receiving and processing asylum seekers and separating economic migrants from refugees fleeing conflict.

Last week, ministers approved a separate plan dating from May for relocating 40,000 refugees.

Britain, which has exercised its right to opt out of the relocation plan, on Tuesday confirmed the arrival of the first tranche of 20,000 refugees it is taking in from refugee camps in Turkey, Jordan and Lebanon.