Three people died and dozens were stranded on a Serbian highway on Friday as heavy snow and severe frost hit large parts of the Balkans, causing travel chaos and power cuts across the region.

In the eastern Serbian town of Pozarevac an elderly couple froze to death in their home, and a man died in the mountainous Sjenica region in the southwest, police said. Temperatures fell as low as minus 15 degrees Celsius (5 Fahrenheit).

Sections of highway linking Belgrade and the southern city of Nis were closed, and remote central Serbia villages remained cut off for a third day. Roads linking Belgrade with Romania's border were also shut, Serbia's Drivers' Association said.

In Bulgaria, heavy snowfall and storms cut electricity to 56 villages and towns across the country, blocked roads and shut the Black Sea port of Varna, authorities said.

Dozens of trucks and cars, some carrying children and pregnant women, were stranded by snowdrifts while avalanches blocked the busy mountain passage of Petrohan.

One municipality in the north-east declared a state of emergency due to difficulties with food supplies.

In Montenegro, dozens of local roads remained closed while repair crews continued work after nearly 48 hours to restore power supplies to the Adriatic port of Bar and the town of Ulcinj near the Albanian border.

Montenegro's largest airport in the capital, Podgorica, was reopened for traffic for the first time in two days.

Croatian media said some roads in mountainous areas were closed, and severe gales halted ferry traffic between the mainland and some Adriatic islands.

In northern Albania, an avalanche blocked 13 cars on Thursday, while the government used helicopters to evacuate the sick from remote areas.

Authorities in Kosovo blamed snow and low temperatures for about 100 traffic accidents in the past 24 hours, in which 16 resulted in injuries.