Grindr, the world’s biggest dating app for the LGBT community, is being sued for allegedly sharing personal information such as people’s HIV status with third parties.

According to the claim, lodged at the High Court in London, “covert tracking technology” was deployed, and highly sensitive information was illegally shared with advertisers.

Law firm Austen Hays says there are more than 650 claimants and “thousands” of UK users were affected.