Freezing temperatures and often blinding snowfall killed 12 more people and caused travel chaos across northern Europe on Thursday, while some of the worst floods in a century devastated parts of the Balkans.

Airports closed down or delayed flights across the continent, roads were coated in an impassible mix of ice and snow and even Europe's vaunted high-speed trains struggled to cope.

Authorities declared a state of emergency in three Balkan countries on Thursday — Bosnia, Serbia and Montenegro — and were evacuating hundreds of people after heavy rainfall caused severe flooding along the Drina River — the worst in 104 years, officials said.

"From my terrace, I no longer see a river, but a lake that has flooded parts of the town's center," said Muris Razanica, whose hillside hotel has a stunning view of the Bosnian town of Gorazde.

"This area is famous for rafting but if this goes on, big ships will be able to dock in Gorazde, it's really unbelievable," he added as the federal army turned out to help evacuate people.

Tourist agencies in Bosnia handed over their rafts so Civil Protection workers could rescue people from apartments in Foca, where water levels have reached the first floor. Those who dared remain on upper floors were given food and water.

On the other side of the river, authorities in Serbia and Montenegro evacuated hundreds of people as the Drina flooded farms and roads. Schools were closed, many people had no electricity or heat, and water supplies were contaminated along the river in all three countries.

In Poland, the cold claimed 10 more lives, bringing the overall deaths there to 18, police spokesman Mariusz Sokolowski said, as police scourged the streets for homeless or drunk people in hopes of saving their lives.

Authorities in Berlin kept subway stations, soup kitchens and heated buses open all night to provide shelter for the city's homeless, and thousands in Germany had to sleep overnight on trains — either stuck by the wild weather or due to a lack of hotel rooms.

Two deaths were reported in Germany — a 73-year-old in Lower Saxony who was struck by a train while trying to clear snow and an 18-year-old in Baden-Wuerttemberg, who lost control of his vehicle on an icy road and crashed into a truck.