Thousands housed in inadequate facilities are at risk as temperatures plummet, warn aid groups and local mayors on islands

A new bout of cold weather across southern Europe has reignited fears for thousands of refugees and migrants sheltered in deplorable conditions in Greece.

Forecasts of freezing temperatures have also been met with trepidation by international agencies, aid groups and local mayors on islands.

“Thousands of people are poised to suffer needlessly in conditions that are becoming increasingly desperate,” said Eva Cossé at Human Rights Watch. “Europe’s failed policies have contributed to immense suffering for people warehoused on the Greek islands.”

Greece was the focus of public outcry this month after shocking footage emerged of refugees on Lesbos living in flimsy, snow-swamped tents as an arctic blast sent temperatures plummeting to -14C. The outcry prompted the government to dispatch a naval ship to temporarily house up to 500 people detained at the island’s vastly overcrowded Moria reception centre. Others were moved into heated containers, hotel rooms and apartments.

Facebook Twitter Pinterest A Syrian girl walks at the refugee camp of Ritsona. Photograph: Muhammed Muheisen/AP

But the measures have proved inadequate and with more severe weather on the way officials, volunteers and human rights defenders fear the worst. Sub-zero temperatures are expected by Thursday.

Since the closure of the Balkan route into Europe, more than 62,000 men women and children have been trapped in Greece, according to government figures. Every day a steady trickle continues to arrive on rickety boats from Turkey, placing increasing pressure on Lesbos and other eastern Aegean islands close to the Asia Minor coast.

“It is not much talked about, but this month alone 900 people have reached Greece,” said Gianmaria Pinto, country director of the Norwegian Refugee Council. “Right now I am on Chios and in one camp there are people living on the beach, in small tents, exposed to the wind and rain. They should be moved to better and more humane conditions and the structures and opportunity for that are only on the mainland.”

Under a controversial deal agreed by the EU and Turkey to curb an influx that surpassed a million people in 2015, Greek authorities last year accepted the introduction of a policy of containment in order to process asylum seekers at accelerated rates. By restricting refugees to islands it was hoped “secondary movement” into Europe could be reduced and those undeserving of asylum easily repatriated to Turkey.

Facebook Twitter Pinterest Afghans try to warm themselves around a fire during a protest demanding better living conditions at a refugee camp in Malakasa, north of Athens. Photograph: Thanasssis Stavrakis/AP

Instead, the policy has backfired with thousands of refugees being forced to endure dire conditions in overcrowded camps while their asylum requests are processed slowly. Many have been in the facilities since March when the EU-Turkey accord was signed.

Despite the allocation of €90m (£77m) in EU funding, the Greek government – with the UN refugee agency and other aid groups – stand accused of failing to properly “winterise” facilities.

On Monday, mayors on the five islands most affected by the flow of refugees appealed to the Greek prime minister, Alexis Tsipras, for relief, arguing it was vital that refugees were transferred to the mainland immediately.

“We shouldn’t tempt fate,” Manolis Vournous, the mayor of Chios, told the Guardian. “There are 50,000 people living on Chios and 2,500 are refugees. That is totally disproportionate. There are huge and negative consequences on our society, on our economy. We have to do something before it is too late.”

Government data released on Tuesday showed 15,248 migrants and refugees – nearly twice the official reception capacity – ensconced on Chios, Lesbos, Samos, Kos and Leros.

Facebook Twitter Pinterest Greece has been urged to improve conditions for refugees on islands and other camps where they are housed in tents despite severe cold weather. Photograph: Giannis Papanikos/AP

In contrast to 2015, when the vast majority were Syrian, most of those now arriving in the country are economic migrants, according to the Greek migration minister, Yiannis Mouzalas.

With the help of smugglers some are making it further into Europe. Many of those freezing this week in sub-zero temperatures in Serbia are thought to have made the journey from Greece, a country regarded by most as a prison.

“Nothing justifies keeping thousands of migrants and asylum seekers in such terrible conditions on the Greek islands,” said Cossé. “Their suffering is not only the consequence of the slow winterisation of facilities but also of a deliberate refusal to transfer more people to the mainland.”