Rescue crews have been clearing major throughways in and around the Turkish city after the storm, named Elpida, blanketed the city of 16 million people with 78cm (31in) of snow in some areas.

Stranded motorists either spent the night in cars, abandoned their vehicles to walk home, or crowded metro trains and public transport. A lucky few were rescued and taken to hotels.

"Nothing is moving. The snow ploughs can't even reach us," Ahmet Odabasi, 40, one of thousands of travellers stranded overnight on a road west of Istanbul said.

"I have been stuck here for 12 hours now. I am lucky that I have gas, food and water," said the motorist, who was driving to Istanbul from the city of Edirne near the border with Greece.

The city's Disaster Coordination Centre, or AKOM, says an Icelandic low-pressure system is behind the cold front and precipitation affecting most of the country.

Istanbul Mayor Ekrem Imamoglu said more heavy snowfall was likely in the city on Tuesday evening, and flurries are expected in the Eastern Mediterranean region through to Wednesday.

On Monday, authorities in Istanbul suspended intercity bus services and blocked travel to the city from Turkey's northwestern Thrace region.

The Istanbul governor's office announced that civil servants would be allowed to stay at home on Tuesday, except for those employed in security, health and transportation sectors.

Schools across Turkey are already closed for a winter break.

Mr Imamoglu said the municipality has provided shelter to about 1,500 homeless people. Another 1,500 people stranded at a bus terminal due to the suspension of intercity services were taken to hotels or hostels.

Teams have left some two tonnes of food for stray cats and dogs, Mr Imamoglu said.

In neighbouring Greece, rescue crews, including the army, worked through the night to evacuate thousands of people stranded in their cars on an Athens motorway.

More than 3,500 people had been evacuated by early Tuesday, some abandoning their cars on foot, but about 1,200 cars remained stuck on the Attiki Odos, the capital's main ring road, government spokesperson Giannis Oikonomou said.

As temperatures fell overnight, soldiers handed out food, water and blankets to drivers, some of whom were stranded in their cars for more than 10 hours.

"We had a very difficult night and a superhuman evacuation effort is underway on Attiki Odos," Mr Oikonomou told Greek television.

"We are still in a very difficult phase, as the forecasts indicate that we will face (weather) difficulties again in a while," he said.

Most public transport has been put out of action in the city by the snowfall.

Authorities declared a public holiday on Tuesday, shutting public offices and private businesses except supermarkets, pharmacies and petrol stations in the greater Athens area and on some islands.

Parts of Athens were hit by power cuts, and the grid operator said crews were working to restore electricity.

Fifteen passengers were injured when a rail transport vehicle tried to pull a train carrying about 200 passengers which had halted in heavy snow in central Greece.

Several islands in the Aegean Sea have also been blanketed in snow.