A sudden onset of harsh winter conditions caused transport chaos in Bulgaria on Tuesday, with one man freezing to death, eight people missing in mountains, 600 villages without power and schools closed.

A 73-year-old man chopping wood in southeastern Bulgaria died on the way to hospital after being snowbound overnight along with 15 other Roma, including eight children, authorities said.

Six hikers including two children plus two rescue workers were missing in the Balkan mountain range near the eastern city of Sliven, where a tempest blew over trees and fences, even lifting roofs off buildings.

Hundreds of vehicles including lorries without winter tyres were stranded along mountain roads, while two trains carrying 100 people were stuck in snowdrifts 10 hours after setting off.

Railways company official Yordan Nedev called on passengers to not travel north "because even if they take the train, they run the risk of not making it to the next station".

After an unusual "Indian summer" with temperatures of up to 28 degrees Celsius (82 degrees Fahrenheit) last week, winter hit the southeastern European country with a vengeance on Sunday, with thermometres now around freezing point.