The arrival of tens of thousands of refugees has plunged Greece into an unprecedented crisis the likes of which no nation could manage alone, the country’s embattled prime minister, Alexis Tsipras, has said.

Speaking as the European commission signalled it was putting together an urgent humanitarian aid package for the country after predictions that more than 200,000 men, women and children will be marooned there by summer, the leftwing leader said Brussels had promised “support and solidarity”.

“We are experiencing the biggest refugee crisis since the second world war,” he told Greek Star TV. “The problem surpasses the powers of the country, the strength of a government and the innate weaknesses of the European Union.”

Close to 30,000 migrants and refugees are now trapped in Greece following the decision of Balkan countries to close Europe’s migrant corridor. The vast majority are Syrians and Iraqis, many women and children, fleeing conflict in the Middle East. “What we are witnessing is the result of the absurd choices of the west,” Tsipras said, referring to western policy over Syria.

By Tuesday more than 8,500 migrants and refugees were said to be stuck at Idomeni at the frontier Greece shares with Macedonia, unable to continue their journey north. Greek armed forces were working around the clock to set up tent cities in fields at the border.

Migrants rest in the passenger terminal after arriving from the islands at the port of Piraeus. Photograph: Milos Bicanski/Getty Images

On Monday there was chaos and commotion in the no man’s land between the two states as Macedonian riot police fired teargas at refugees attempting to break through a border fence. Children, including toddlers, received emergency aid from Médecins Sans Frontières and other medical charities after suffering respiratory problems.

“It rained throughout the night and a lot of tents aren’t waterproof but the situation this morning is calm,” said Caroline Haga, a delegate with the International Federation of Red Cross, at the scene. “The military has been distributing food and registering refugees and pitching tents in new camps in the area.”

The rapid build-up of migrants at Greece’s northern borders risks creating a humanitarian disaster, the United Nations high commissioner for refugees said on Tuesday.

The UNHCR called for better planning and accommodation for those stuck in Greece, including the 8,500 at Idomeni. “Europe is on the cusp of a largely self-induced humanitarian crisis,” the UN refugee agency’s spokesman, Adrian Edwards, said.

“The crowded conditions are leading to shortages of food, shelter, water and sanitation. As we all saw yesterday, tensions have been building, fuelling violence and playing into the hands of people smugglers,” he said.



The UNHCR also urged all EU member states to reinforce their capacity to register and process asylum seekers through their national procedures as well as through the European relocation scheme. “Greece cannot manage this situation alone,” Edwards said.

The crisis is playing out across Greece from Athens’s port of Piraeus in the south to the port of Kavala in the north and cities in between, where panic-stricken authorities have reportedly been working through the night to establish housing facilities for the new arrivals. Men, women and children were being housed in army barracks, sports arenas, parks and public buildings.

Government officials said the plan was to accommodate 50,000 as soon as possible. But with the rate of migration showing no signs of abating soon, Tsipras’s two-party coalition is clearly struggling to keep up with events. Authorities on outlying Aegean islands that have borne the brunt of the arrivals from the Turkish coast are seeing as many as 3,000 people arrive every day. Passenger ferries, normally the preserve of tourists, were expected to land at Piraeus with another 2,500 migrants and refugees from the islands of Lesbos and Chios on Tuesday. At least another 500 were sleeping out in the open in conditions that have become increasingly squalid in Victoria Square in downtown Athens.

Migrants carry belongings in Athens’ Victoria Square. Photograph: Vadim Ghirda/AP

With Greece’s public services hard hit by the country’s debt crisis, NGOs have rushed to fill the gap. By 10am on Tuesday, a group of volunteers with the Hellenic Red Cross had begun distributing packages of dry food and water to hundreds of Syrians, Afghans, Iranians and Iraqis in Piraeus. “There is a huge problem with children being sick,” Panaghiotis Bouras, a social worker with the group, told the Guardian.

“A lot of them arrive exhausted from the journey. The only thing they want to know is when the border [with Macedonia] is going to open again. The truth is, we have no idea what to tell them.”

Macedonian officials insisted that borders would remain sealed “until further notice”.

“The entry procedure for migrants is to remain suspended,” said Marijan-Pop Angelov at the Macedonian embassy in Athens. Earlier the government in Skopje had announced: “It will resume upon restoration of order on the other side of the border and of adequate conditions for controlled entry.”

Greek officials admitted Athens was also preparing an emergency health plan to “protect the Greek public” in the event of an outbreak of disease. The Greek daily Ta Nea, citing European commission sources in Brussels, reported that an aid package of as much as €700m (£545m) could be given to Greece for relief purposes in the coming days.