Europe can expect millions more refugees to flood in from Syria as the war between Bashar al-Assad and rebel groups has turned the country into a 'living hell', a UN official has warned.

Currently in the grip of the worst refugee crisis since the end of the Second World War, the UN has warned it is being fuelled by the Syrian war which has uprooted half its pre-war population.

But with the situation in Syria deteriorating, far more are likely to come, warned Peter Salama, head of the UN children's agency's Middle East and North Africa division.

Europe can expect 'millions and millions' more refugees in the coming years due to the deteriorating situation in Syria. Pictured are refugees breaking through a police cordon in Macedonia

Hungarian police attempt to restrain migrants attempting to board a train bound for Vienna, Austria

Salama suggested 'millions and millions' more refugees could make their way to Europe in the next few years if the conflict did not end.

About 70 per cent of the 3,000 people landing on the Greek islands daily are Syrians fleeing the war, while around half of those to cross the Mediterranean are trying to escape the conflict.

Salama said the country had now become a 'living hell' for children, and pointed out that millions of people displaced within Syria are living in horrendous conditions, while more than four million Syrian refugees are living in neighbouring countries, with rapidly dwindling aid budgets to support them.

'It certainly stands to reason that there could be millions and millions of more refugees leaving Syria into surrounding countries and ultimately to Europe and beyond,' Salama said.

It comes as shocking new figures from the Syrian Observatory of Human Rights suggest half of the country's population has now been uprooted by the conflict.

An estimated 10.6 million people have either been displaced from their homes within Syria, become international refugees, or killed. Another 10.6 million remain in their homes.

However, UNHCR spokesman William Spindler has downplayed Salama's numbers, insisting that while UNHCR's estimate of 400,000 arrivals this year could likely be surpassed, 'we are far yet from millions'.

'I think we should be very careful about inflating the numbers. There is a crisis at the moment because of the chaotic way in which Europe has responded, not because Europe lacks the resources,' he said. 'Europe has the means to deal with this situation.'

Half of Syria's pre-war population has now been uprooted, with 10.6 million people either displaced or killed

Hundreds of migrants set off on foot through Austria after train services were suspended due to the influx

A UN official has warned Syria has become a 'living hell' for children due to the civil war which has raged since 2011. Pictured is a migrant boy at a registration camp in Macedonia

A man carries a small boy through the rain on his shoulder as they make their way to Hungary from Serbia

A spokesperson for the World Food Programme has today warned refugees in Jordan and Lebanon have reached 'rock bottom' and would rather return to Syria.

According to The Guardian, Dina El-Kassaby said food voucher cuts were the 'straw that broke the camel's back'.

'This is several years of struggle and systematically finding, month-by-month, that forms of assistance are being cut off.

'And now the one that has lasted the longest - food assistance - is one that we just can’t keep up any longer unfortunately.'

Meanwhile, the United Nations on Friday hailed a European Union plan to distribute 160,000 refugees around the continent, but warned it would not be enough and tens of thousands more places are needed.

UN refugee chief Antonio Guterres called last week on European countries to take around 200,000 refugees by the end of the year as part of a 'massive relocation programme'.

EUROPE'S REFUGEE CRISIS REACHES UNPRECEDENDENTED LEVELS A group of refugees walk through rain and freezing temperatures as they make their way to Hungary from Serbia Around 70 per cent of the 3,000 landing on the Greek islands every day are from Syria.

More than 430,000 refugees and migrants have crossed the Mediterranean to Europe so far this year. Of these, 2,748 have drowned.

An estimated 309,356 people have arrived by sea in Greece, with another 121,139 arriving in Italy, 2,166 in Spain and 100 in Malta.

This is compared with 197,940 people who arrived by sea in those four European countries in all of 2014.

The number of those uprooted by the Syrian civil war, which began in 2011, is 10.6million - half of the country's pre-war population.

Of these, 310,000 have been killed and more than 4 million displaced abroad.

The number of Syrians seeking refuge in Europe rather than neighbouring countries has doubled in the past year.

Germany and Sweden remain their preferred destinations, followed by France, Spain and Britain. Advertisement

'The proposed relocation scheme for 160,000 refugees from Greece, Italy and Hungary would go a long way to address the crisis,' UNHCR spokesman William Spindler told reporters Friday, warning though that "our initial estimates indicate even higher needs."

Eastern European countries have balked at the EU quota plan, but UNHCR insisted it could only work if all the member countries took part.

It also said more was needed to relieve pressure on frontline states, calling for "large-scale emergency reception, assistance and registration efforts in the countries most impacted by arrivals."

UNHCR earlier this week appealed to donors for $30.5 million (27.1 million euros) to help it address the refugee crisis in Europe through 2016, estimating that some 400,000 people will have crossed the Mediterranean by the end of this year, and another 450,000 will do so next year.

Europe is struggling to cope with the worst refugee crisis since World War II, with more than 380,000 migrants and refugees having crossed the Mediterranean since January. Around 2,850 have perished trying.

Half of all crossings so far this year have been made by people fleeing Syria's devastating civil war, which after four and a half years has claimed 240,000 lives.