The death toll from the cold snap hitting parts of Europe rose to at least 65 on Wednesday as Bulgarian authorities reported seven fatalities.

They included a couple in their 80s, the only inhabitants of a village in the mountainous region of Smolyan in southern Bulgaria, who were found dead in their home on Saturday.

Elsewhere in the country two Iraqi migrants died in a snowstorm, a couple both aged 55 were killed by carbon monoxide poisoning caused by faulty heating and a homeless man froze to death.

Temperatures sank to minus 18 Celsius (minus 0.4 Fahrenheit) in the capital Sofia and Bulgarian authorities said electricity and gas demand have reached 20-year highs.

Most of the deaths over the past week have been in central and south-eastern Europe, with homeless people and migrants stranded in Greece, Serbia and elsewhere most at risk.

In Turkey snow over the weekend paralysed Istanbul, forced the closure to ships of the Bosphorus Strait and the cancellation of hundreds of flights.

Maritime traffic on rivers including the Danube, one of Europe's busiest waterways, has also been severely hampered.

In Greece on Wednesday, having been caught off guard and facing heavy criticism, the government sent a navy transport ship to the island of Lesbos, to house around 500 migrants still sleeping in tents.

Greece also announced a nationwide week-long hunting ban because of the cold weather gripping most of the country.

burs/jph/adm