The UN Refugee Agency (UNHCR) on Tuesday said the number of refugee and migrant arrivals to Greece hit half a million, warning of continued chaos unless migrant reception in Greece was strengthened and relocation was expedited.

“In Greece, the number of sea arrivals this year has now passed the half-million mark with the arrival on the Aegean islands of nearly 8,000 people, bringing the total to some 502,500.

“The total number of arrivals so far in Europe via the Mediterranean is now over 643,000,’’ Melissa Fleming, UNHCR spokesperson told newsmen.

She said the spike in arrivals in Greece had sharply increased pressure on reception centres on the islands.

However, many of the refugees and migrants were desperate to quickly move onwards, fearing subsequent borders would close.

“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,’’ she added.

According to UNHCR, after chaotic and miserable scenes over the past few days, borders along the Balkan routes have reopened.

On the Serbian border with Croatia, some 3,000 people were left waiting amid uncertainty in the rain from Sunday until Monday without shelter and with minimal assistance on hand.

No fewer than 123 people have died or gone missing in Greek territorial waters so far this year (in all, at least 3,135 have perished in the Mediterranean to date in 2015).

UNHCR expressed concern over the potential for this number to rise further as people try to beat the onset of winter and fears of new border closures.

The agency also urged search and rescue operations to be further strengthened in the area to reduce risks.

“To address the current situation in Europe, various measures of stabilisation are needed in countries of first asylum and all countries of secondary movements to reduce irregular secondary movements,’’ it added.

However, these measures include strong support to countries hosting the vast majority of Syrian, Iraqi and Afghan refugees and an information campaign informing of the dangers of the sea journey.

The measures also include the development of legal pathways to seek protection in Europe.