London (AFP) - A British media watchdog on Friday fined a top pro-Brexit campaign and an insurance company headed by its donor for violating data protection rules.
The Information Commissioner's Office (ICO) said the Leave.EU lobby group funded by Arron Banks used the personal data of his insurance company's clients to send them targeted political ads.
Leave.EU and Eldon Insurance -- known as GoSkippy Insurance at the time -- were fined a total of Â£120,000 ($157,000, 137,000 euros).
The amount was reduced by Â£15,000 from the fine originally announced in November following an appeal.
The ICO concluded that Leave.EU used Eldon Insurance customers' details to unlawfully send them nearly 300,000 messages backing Britain's split from the European Union during the 2016 campaign.
It said Eldon Insurance simultaneously broke the law by sending Leave.EU subscribers more than a million marketing messages without their consent.
"It is deeply concerning that sensitive personal data gathered for political purposes was later used for insurance purposes; and vice versa," Information Commissioner Elizabeth Denham said.
Denham said both groups have informed the ICO that they had made improvements to how they work with clients' data.
The ICO intends to conduct an audit "to determine how they are using customers' personal information," she said.
Banks is usually heavily active on Twitter but issued no immediate response.
The businessman tweeted in November that "we may have accidentally sent a (political) newsletter to customers" of his insurance firm.
"Gosh, we communicated with our supporters and offered them a 10 percent Brexit (insurance) discount after the vote! So what?" he also tweeted at the time.
Vote Leave was the official and slightly larger pro-Brexit campaign, while Leave.EU was the biggest unofficial lobby group.
It focused heavily on putting an end to migration and received backing from former UKIP leader Nigel Farage.
The pro-Brexit camp won by a 52 to 48 margin.
Britain is due to leave the bloc after 46 years on March 29.