Hungary closed the Danube to river traffic Friday because of thick ice, bringing shipping to a near standstill on Europe's busiest waterway, as the continent's cold snap death toll reached past 540.

"Shipping was ordered stopped overnight Thursday to Friday because of conditions created by icing along the Hungarian part of the river," Istvan Lang, who heads the national technical supervisory body OMIT said.

"All ships still underway must immediately head for the closest harbour," Lang, quoted by MTI news agency, said.

Other countries along the Danube, including Austria, Croatia, Serbia, and Bulgaria, had already suspended river traffic because of the freeze.

The 2,860-kilometre (1,780-mile) river, which flows through 10 countries and is vital for transport, power, irrigation, industry and fishing, was nearly wholly blocked from Austria to its mouth on the Black Sea.

In Hungary, 60 to 70 percent of the river was frozen, with only ice-breakers remaining in action, especially in the south of the country, officials said.

The cold snap, which started two weeks ago, is expected to continue until mid-February, forecasters said.

In neighbouring Serbia, "the situation is relatively better then in the previous days as the snow stopped and the emergency services will focus today on delivering food to endangered regions," Predrag Maric Serbia's chief emergency official told state television.

Helicopters were to deliver food to remote areas of southwestern Serbia which have been trapped in snow for days, he added. Some 70,000 people were still cut off from the outside world.

Temperatures in Serbia hit a new low Friday with with minus 26 degrees Celsius (minus -14.8 Fahrenheit) in the northern town Sombor and minus 15 degrees Celsius in the capital Belgrade at 0500 GMT.

In Bosnia, 20,000 homes in the southern towns of Mostar and Nevesinje and surrounding villages were connected again to the electrical grid after three days without power, Pero Pavlovic of the Civil Protection services said Friday.

"Some small hamlets are still without electricity but it should be re-established shortly," Pavlovic added.

In Romania, 13 died of cold overnight Thursday to Friday, bringing the overall toll to 57 since the start of the cold spell, officials said.

Over 20,000 people are cut off by snow in the east of the country with food supplies runing out, they added.

In some villages, such as Varasti, in the south of the country, where four metres of snow (13 feet) have fallen, inhabitants had to tunnel their way out of their homes or exit through top windows.

"I fear all my hens and turkeys are dead," said Varasti resident Marin Boacana, 60, pointing to his snow-covered chicken coop.

In Italy, where the cold has killed more than 45 in the past 10 days, snow started to fall anew on Friday.

A 42-year Romanian woman, believed to be sleeping rough and who had found shelter in a cave in the Rome suburbs, was found frozen to death, while a man was reported attacked by scavenging stray dogs near Rimini.

Motorways banned some heavy truck traffic in the northeast of the country, while rail services and Bologna airport experienced delays.

In Rome, where forecasters predict up to 30 centimetres (11 inches) of fresh snow, all schools were closed on Friday.

Residents stocked up on food, fearful of a repeat of the disruption seen last weekend. At the Porta Portese street market, snow chains have been selling for up to 400 euros ($528) after city authorities ordered all cars to carry them.

The Abruzzi mountains, in central Italy, the Marche region, in the east, and towns along the western coast were all blanketed in snow.

On the island of Sardinia, a man died apparently from hypothermia shortly after coming out of a hospital dressed only in pyjamas and slippers.

In Bulgaria where 32 have died, authorities continued a massive relief effort in the southeastern village of Biser, submerged under the icy waters of a nearby dam that burst on Monday. Ten died in the flood, with the last two bodies recovered Friday from rubble.

At least 135 people have died of the cold in the Ukraine, 82 in Poland, 46 in Russia, 25 in the Czech Republic, 24 in Lithuania, and 16 in Serbia.

In France, the death toll increased to at least eight after Paris authorities said that two homeless men, a Pole and a Romanian, had died of cold in the capital over the past week. And a nuclear reactor at the Cattenom plant shut down because of a fault, placing fresh pressure on the already strained national power grid Friday, state energy giant EDF said.

Meanwhile Azerbaijan set up shelters for homeless people in the capital Baku on Friday for the first time since World War II, after five died of the cold.