The number of refugees, who have arrived in Greece this year has crossed the 500,000 mark, with the European nation struggling to handle the crisis. The UN has said there is a sharp increase in migrant numbers ahead of the imminent cold weather.

As arrivals continue to swell, pressure to set up "hotspot" reception centres, is also mounting on EU authorities. According to the UN's High Commissioner for Refugees (UNHCR), the number of migrants landing on Greek shores has risen to 8,000 a day.

"It is of utmost importance here, as in other parts of Europe, that reception conditions be adequate to the task. Without this essential element, the relocation programme agreed by Europe in September is in serious peril and may fail," the UN agency's spokesperson, Melissa Fleming told reporters.

"Obviously Greece is doing what it can, it's pulling in additional police. But we need to repeat over and over again that it is of utmost importance here that reception conditions be established and be adequate to this enormous task. Without this essential element, the relocation programme that was agreed by Europe in September is in serious peril and may fail. One system can't work without the other," added Fleming.

The continuing conflict in the Middle East and Africa has forced hundreds of thousands of migrants, to flee their homes and seek better living conditions in Europe. The EU has witnessed record levels of migrants this year. The UN estimates, 3,135 people have perished in the Mediterranean waters attempting to make it to Europe on small boats.

Further, the International Organization for Migration (IOM) has expressed serious concern over the worsening situation as the number of migrants is increasing rapidly. The organisation's spokesperson, Joel Millan, said: "We are alarmed at how much this is continuing through the cold weather. We are reporting 25 deaths in the Aegean (Sea) this week, many of them children."

The EU has already agreed to resettle about 160,000 asylum-seekers from Italy to Greece to other European nations. Nonetheless, there is a growing demand for the Union to do more on the crisis.