Flight operations at Istanbul Airport, Europe's busiest, were mostly suspended through Tuesday afternoon due to heavy snowfall that has caused travel chaos across Turkey's biggest city.

The airport managed to open only one runway to allow flights from overseas such as the US, Canada and Mexico land, operating firm IGA and national carrier Turkish Airlines confirmed to dpa.

No planes are planned to take off from Istanbul Airport until midnight on Tuesday, a Turkish Airlines spokesperson said, adding there were no major disruptions at the smaller Sabiha Gokcen Airport, on the Asian side of the city.

A suspension of flights to and from the bigger airport was first imposed on Monday as the winter weather moved over the city of nearly 16 million.

The operating firm said it provided free wi-fi and food discounts as well as distributing 3,600 blankets to passengers stranded.

Meanwhile, main roads in Istanbul were open to traffic, Istanbul Mayor Ekrem Imamoglu said on Twitter, citing efforts against "extraordinary" weather.

Local media reported that many travellers had to spend the night in their cars in Istanbul. Some NGOs joined efforts to distribute food to those stranded.

Istanbul Governor Ali Yerlikaya said intercity travel buses will not be allowed to operate from Istanbul until Wednesday morning. He urged car owners to remove private cars on the sides of roads.

Further snowfall is expected in Istanbul and the rest of Turkey later on Tuesday.

Across the Aegean Sea from Turkey, air and ground traffic were also crippled in the Greek capital Athens due to the same weather system.

Parts of Greece were experiencing similar traffic snarls on Tuesday due to snowfall. Thousands of motorists travelling around the Athens area had to spend the night in their cars, while extensive delays and cancellations were reported at the city's airport.

The military was deployed to get people out of their cars and put them up in hotels. At least 3,500 people were rescued on Tuesday while respective firms said those stranded on privately-owned roads will get 2,000 euros in compensation.

Electricity is not back yet in many places in Greece while schools and public institutions were reported to remain closed through Wednesday.

dpa