A hacker hijacked the Twitter account of Arron Banks, chairman of the pro-Brexit UK political campaign organization Leave.EU, and leaked his private message history online earlier this week.

The BBC yesterday reported that the culprit had access to thousands of private messages that had been sent and received by Banks over several years. The Register further reported that the hacked Twitter account was used to spread links to a Mega.nz download page that hosted a dump of the messages. Banks’ account has been suspended and the file is reportedly no longer available online.

The Guardian reported that the attack involved illegal access to Banks’s email address, and quoted a Leave.EU spokesman as saying that a SIM swap also took place.

Banks directed his outrage toward Twitter, accusing the social media company of mounting an inadequate response.

“I became aware last night that my Twitter account had been hacked and that persons involved have posted personal data obtained illegally via Twitter,” Banks wrote on the official Twitter page of Leave.EU. “The matter has been reported to the police.”

“Twitter were [sic] notified 12 hours ago, and despite repeated requests they have taken no action to deactivate the account or remove the illegal data downloads,” Banks continued. “Despite the obvious lack of security at Twitter related to personal data, they have deliberately chosen to leave personal data in the public domain.”

Per the BBC, Twitter said it had “taken steps to secure the compromised account” and “will continue to take firm enforcement action in line with our policy which strictly prohibits the distribution on our service of materials obtained through hacking.”

In February 2019, the UK’s Information Committer’s Office levied a £120,000 fine against Leave.EU and Eldon Insurance — a company founded and owned by Banks — for breaching data protection laws. Leave.EU reportedly sent Eldon customers political marketing messages without their consent, and Eldon sent unsolicited emails offering discounts to Leave.EU subscribers.