A cold wave across Europe has left at least 23 dead in the past two days, including several migrants and homeless people, authorities said Saturday, with the frigid temperatures expected to continue through the weekend.

Russia meanwhile celebrated the coldest Orthodox Christmas in 120 years, and even Istanbul was covered with a blanket of snow.

Ten of the latest victims of the cold perished in Poland where temperatures were as low as minus 14 degrees Celsius (seven degrees Fahrenheit) on Saturday.

"Seven people died on Friday in what was the deadliest day this winter," said spokeswoman Bozena Wysocka from the Polish government centre for security (RCB).

"We recorded three other victims the previous day," she said. "This takes to 53 the number of hypothermia victims since November 1."

In Italy in the past 48 hours the cold has been blamed for seven deaths, including five homeless people, two of them Polish nationals, authorities said.

There was heavy snowfall in central Italy and also in the southeast where the airports at Bari and Brindisi as well as in Sicily were closed Saturday morning.

Prague's emergency services reported three deaths -- two homeless people and a parking lot guard -- overnight in the Czech capital, the coldest night so far this winter.

Temperatures in Moscow fell to minus 30 degrees overnight and to minus 24 in Saint Petersburg where police found the body of a man who had died of hypothermia.

And in Bulgaria on Friday the frozen bodies of two Iraqi migrants were discovered by villagers in a mountain forest in the southeast of the country near the border with Turkey.

Authorities expect the toll to rise as weather conditions are set to remain unchanged this weekend.

- Snow in Istanbul -

The heavy snowstorms reached Turkey, paralysing its biggest city Istanbul where almost 65 centimetres (25 inches) of snow fell, forcing hundreds of flights to be cancelled on Saturday.

Coastguards also ordered a halt to shipping traffic in both directions through the Bosphorus Strait -- one of the world's busiest sea thoroughfares -- and the municipal ferry service between the European and Asian sides of the city was suspended.

Greece likewise has seen fierce cold weather over the past week. In the north near the Turkish frontier a 20-year-old Afghan migrant died of the cold on Tuesday.

With more than 60,000 mainly Syrian refugees on its territory, Greece has moved many migrants to prefabricated houses and heated tents.

The temperature in Athens on Saturday was zero degrees Celsius and down to minus 15 in the north of the country.

The coldest temperature in Europe so far this winter was recorded on Friday in the Swiss village of La Brevine at minus 29.9 degrees.

That was still much milder than the village's record of the coldest temperature ever in Switzerland at minus 41.8 degrees on January 12, 1987.