THE country’s leading anti-independence campaign has suffered a damaging security breach, with the leaking of hundreds of donor names and contact details.

Scotland in Union said it had reported the matter to the police and information watchdogs.

The names, addresses, emails, home and mobile phone numbers of hundreds of confirmed and potential donors were leaked at the weekend to pro-independence websites.

Scotland in Union now faces a possible investigation and sanction by the UK Information Commissioner’s Office, which enforces the safe handling of personal data.

Wings Over Scotland, the Nationalist website run by controversial Bath-based blogger Stuart Campbell, posted redacted images of a donor spreadsheet showing dates and amounts.

Mr Campbell claimed several members of the aristocracy were among those giving money to Scotland in Union, but did not name them.

He later removed the images after receiving a letter from lawyers acting on behalf of Scotland in Union, which he said “made all manner of dire threats, some serious and some farcical”.

The Yes-supporting Bella Caledonia website also said it had received the “data dump”, which it said was full of the rich and landed classes, describing it as “like Debrett’s on speed-dial”.

Scotland in Union was set up shortly after the 2014 independence referendum in order to resist a second vote on the constitution.

The cross-party group has a reputation for lavish events and elite backers, raising around £350,000 from a £250-a-plate dinner at Edinburgh’s Prestonfield House Hotel in 2016.

With guide prices up to £12,500, auction lots on the night included stays at private safari lodges in Kenya and Botswana, French and Swiss skiing chalets, a polo festival in India, and a plethora of deer stalking, fishing and grouse shooting events in the Highlands.

There was also a £100-a-ticket raffle to win a Mini Cooper convertible, a VIP tour of the Rangers FC training facility and seats in a director’s box courtesy of Paul Murray, and a signed copy of the JK Rowling novel A Casual Vacancy.

Last January, with speculation mounting Nicola Sturgeon planned to call another referendum because of Brexit, it hired former Labour MSP Graeme Pearson as its chief executive.

At the time, he said he had “never heard” of the group, which boasts 25,000 supporters.

Paid £50,000 for a commitment of one and half days per week, he quit within seven months.

He was replaced in August by another former Labour politician, Pamela Nash, who was the MP for Airdrie & Shotts from 2010 to 2015.

In December, a group of former Scotland in Union staff set up a rival pro-Union campaign called UK Unity with a more aggressive “populist” tone and a vehement pro-Brexit stance.

UK Unity is led by David Clews, who was elected as a Tory councillor in Renfrewshire in 2007, defected to Labour in 2011, and left elected politics in 2012.

A spokesperson for Scotland in Union said: “All information on our supporters is protected and held securely in accordance with best practice and we regret internal documents have been shared with external parties.

“We have reported the matter to both the police and the Information Commissioner.

“We have taken all necessary steps to make our affected supporters aware and will continue to investigate how these documents have been misused.”