COMMUNICATIONS to Shetland have been completely shut down after a subsea cable was damaged. 

Police have since declared a major incident after the south subsea cable linking the islands and the mainland was cut. 

The force said phones, internet and computers could not be used and that officers were patrolling to help reassure residents. 

The cause of the cable damage is unknown. 

Repairs to another cable connecting Shetland and Faroe are ongoing after being damaged last week. 

A BT Group spokesperson said: "Due to a break in a third-party subsea cable connecting Shetland with the Scottish mainland, some phone, broadband and mobile services are affected.

"Engineers are working to divert services via other routes as soon as possible and we'll provide further updates. 

"Our external subsea provider is also looking to restore their link quickly. Anyone who needs to call 999 should try their landline or their mobile, even if they don't have signal from their own mobile provider. 

"We're sorry for any inconvenience." 

Police Scotland is now in talks with partners including the Scottish Fire and Rescue Service and HM Coastguard to help bring additional emergency support to the island. 

Commenting on the incident, First Minister Nicola Sturgeon tweted: "This is a very serious situation for Shetland. @scotgov resilience committee has met and is working closely with partner agencies to ensure support for those who need it, and that the cable damage can be repaired and services restored asap."

Chief Inspector Jane Mackenzie told BBC Good Morning Scotland that police would be more visible on the island in the meantime. 

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She said: “We’re still trying to work to establish the full extent of the problem – we know there are some telephone lines working, 999 lines are believed to be working and some mobile networks are still working. 

“So anyone calling 999 should be able to do so from a mobile phone. What we would ask is if you have an emergency you should first try a landline or mobile to call 999. 

“If that doesn’t work, you should flag down an emergency service vehicle that isn’t using their blue light or attend either a police station, hospital, fire or ambulance station to report the emergency."

Mackenzie also urged the public not to use phone lines for non-urgent calls and to check on elderly and vulnerable people frequently as assistance alarms may not be operating as effectively. 

Responding to the cutting of the subsea cable, Scottish Liberal Democrat MSP Beatrice Wishart said: “I want to begin by expressing my gratitude to all the engineers and emergency services who have stepped up so quickly to try and resolve this disruption and reassure residents. 

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“My constituents are understandably concerned by the news this morning. There is an extremely limited telephone and broadband service, which has huge repercussions for families and businesses across the islands. 

“I am in limited contact with the Scottish Government to keep me updated on what can be done to resolve the incident as swiftly as possible. 

“This kind of disruption points to the fundamental vulnerability of our current island infrastructure. 

“We need long-term changes to create a resilient service that can guarantee residents connectivity, reliability and safety.”

This is not the first time there has been a break in one of the subsea cables which links the remote communities to the mainland. 

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One of the cables suffered a serious break in 2014, though it was not as serious as the one which occurred on Thursday. 

According to ISP Review – a website for internet service provider related news – the most common cause of the breaks is “fishing trawlers”. 

An article on the 2014 break reads: “Related cable breaks can occur for a variety of different reasons, although the most common cause is fishing trawlers.”

The cable damaged last week is set to be repaired on Saturday, according to Faroese Telecom's head of infrastructure Páll Vesturbú.

He said: "The damage is affecting most of telecom services to Shetland. There are some services still working but we will try to establish more services during the day if that's possible. 

"We expect it will be fishing vessels that damaged the cable but it is very rare that we have two problems at the same time."