As winter approaches, the Greek government is being urged to act to prevent the possible deaths of refugees trapped in squalid camps.

A dozen human rights organisations, including Oxfam and Human Rights Watch (HRW), have united to highlight the issue, stressing Greece needs the support of EU leaders to end the policy of “containment”, which restricts asylum-seekers to the islands while their claims are processed.

Greece’s Prime Minister Alexis Tsipras has been urged to transfer the refugees to better living conditions on the mainland by the time winter officially starts on 21 December.

“This remains a matter of life and death,” Jana Frey, Greece’s director for the International Rescue Committee, said in a statement.

“There is absolutely no excuse for the conditions on the islands right now – thousands of people crammed into overcrowded and desperately under-resourced facilities.”

In pictures: Refugees on the Greek island of Lesbos Show all 12 1 /12 In pictures: Refugees on the Greek island of Lesbos In pictures: Refugees on the Greek island of Lesbos Refugee children at the Moria camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees queuing for food at the Kara Tepe camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees' tents at the Kara Tepe camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees at the Oxy transit camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees waiting to board ferries to the Greek mainland in Mytilene, Lebos In pictures: Refugees on the Greek island of Lesbos Refugees waiting to board ferries to the Greek mainland in Mytilene, Lebos In pictures: Refugees on the Greek island of Lesbos Refugees waiting to board ferries to the Greek mainland in Mytilene, Lebos In pictures: Refugees on the Greek island of Lesbos The graves of drowned refugees in Mytilene, Lesbos In pictures: Refugees on the Greek island of Lesbos A building used to house unaccompanied children at the Moria camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees queuing to register at the Moria camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees at the Moria camp in Lesbos In pictures: Refugees on the Greek island of Lesbos Refugees arriving on smugglers' boats from Turkey in Lesbos

Migrant “hotspots” at Lesbos, Chios, Samos, Leros, and Kos are almost 7,200 over capacity, with close to 13,000 people, including many women and children, in facilities with a capacity of just 5,576, according to the groups. The majority of refugees are believed to be Syrians and Iraqis fleeing their war-torn countries.

Those stuck in the camps live in harsh and often unsanitary conditions, often sleeping on the ground, exposed to the cold and rain, with limited access to proper toilets and showers, while women are forced to share tents and containers with unrelated men, risking their safety, the groups said.

Last winter, at least three men are known to have died on Lesbos, with their deaths attributed to carbon monoxide poisoning from makeshift heating devices used to warm the freezing tents, the umbrella group said.

The policy of containment was put in place as part of the EU-Turkey deal in March 2016, forcing asylum seekers arriving on the Greek islands to remain there until their claims are decided.

The groups claim forcing asylum-seekers to remain in such poor conditions cannot be justified, with some who arrived in Greece during the early days of the deal having remained there for 20 months. The deal was intended to send back failed asylum seekers to Turkey, but deportations have been far outstripped by the numbers who continue to arrive, they said.

Nicola Bay, head of Oxfam in Greece, said that by trying to preserve the EU-Turkey deal, the Greek islands “have been transformed into places of indefinite confinement for asylum seekers who have risked their lives in search of safety and a better life in Europe.”

“The EU and the Greek government need to start putting people’s lives ahead of politics and uphold Europe’s commitment to human rights.” she concluded.

Responsibility for running the camps now lies with the Greek Government, who took over from the various NGOs in August this year, redirecting EU funding of the refugee crisis from charities to the Greek authorities.