ISLANDERS were urged to stay at home after thousands were left without power yesterday after the network was damaged by heavy snow.

Keith Brown, the justice secretary and lead minister for resilience reinforced a message sent by Police Scotland to stay indoors as warnings emerged that Shetland's electricity cuts may not be resolved for days.

Up to 6000 were hit by power outages on Shetland with some 2000 reconnected on Monday night - as Scotland recorded its coldest night of the year.

Scottish and Southern Electricity Networks (SSEN) Distribution has warned that the issues are likely to extend to the end of the week.

SSEN said their teams have described the conditions as the “worst they’ve seen in over 20 years”.

The Met Office issued yellow snow and ice warning covering northern Scotland, Orkney, Shetland and Hebrides from midnigh last night until noon tomorrow.

Many schools were closed in Shetland, Highland, Moray and Dumfries and Galloway due to the effects of the weather.

Meanwhile police were warning drivers not to leave their cars while defrosting them following the theft of two vehicles in West Lothian.The drivers had left their cars after switching them on to let the heaters defrost windows.

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Travel problems are set to be exacerbated again today with the second of four strike days carried out by railway workers which will severely restrict the rail network.

The strikes will continue on Friday and Saturday in a bitter dispute over pay.

Temperatures in parts of Scotland are not expected to climb above freezing in daylight hours for the rest of the week.

Overnight a temperature of 117.3C was recorded in Braemar, Aberdeenshire. -15C was recorded at Balmoral, -14C at Aviemore, -13C at Dalwhinne and at Fyvie Castle it was -12C.

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About 3,800 homes remained without without power in Shetland at 11am yesterday with areas affected including Voe and Brae in the north mainland along with the islands of Yell, Unst and Whalsay.

They say the majority of faults have been caused by ‘line icing’, a rare occurrence where, at a certain temperature, snow and ice sticks to overhead power lines and accumulates, adding significant weight to the lines and causing them to break. SSEN said this has caused multiple points of damage on Shetland’s overhead line network.

Mr Brown declared the Shetland issues as a "major incident" warning that many properties will face days without power.

“Our utmost priority must be to ensure that people, especially the most vulnerable, are safe and warm. SSEN have contacted all priority customers and Shetland Islands Council has identified vulnerable people who may need extra support. It is also considering how buildings such as community centres could be used to provide respite centres if needed," he said.

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“I would urge people to heed the Police Scotland advice to stay at home, find ways to stay warm, check in on neighbours, friends and family, and listen to the local radio or follow social media for updates.”

Teams from SSEN have been out to continue restoring power to homes impacted by what it called “extreme weather conditions” in Shetland.

An SSEN spokesman said: "All efforts are being made to restore customer supplies as soon as practically possible, but our teams are experiencing extremely challenging conditions. Weather-related travel delays are also restricting the ability to send additional operational teams to the islands.

"We expect to make progress today in restoring customers on Yell and Unst through repair of the main network, but due to the extent of damage, significant travel restrictions and continued issues accessing fault locations, full restoration of customers is likely to extend to the end of this week.

"This is particularly the case for outlying islands and localised faults and further information will be shared once all faults are assessed."

Customers were warned not to approach any damaged equipment and instead, to report it.

SSEN said that engineers have had to be drafted in from the mainlaind to Shetland to assist with restoration efforts.

Mark Macdonald, head of region at SSEN Distribution, said: “Following the impact of significant snowfall and extreme weather conditions in Shetland over the past 24 hours, our engineers have been out since first light this morning to continue restoration efforts. Access issues, complex repairs and ongoing adverse weather have resulted in significantly challenging conditions for our local teams.

“We’ve seen extensive damage to the overhead power lines connecting homes and businesses, including multiple points of damage caused by snow and ice accretion which was not forecast.

"I'd like to reassure our customers we’re doing everything we can to restore power as quickly as possible and would encourage anyone who may be in a vulnerable situation to contact us on the power cut helpline."

Temperatures in parts of Scotland are not expected to climb above freezing in daylight hours for the rest of the week.

Overnight a temperature of -15C was recorded at Balmoral, -14C at Aviemore, -13C at Dalwhinne and at Fyvie Castle it was -12C.