Millions of iPhone users could be eligible for payouts, following the launch of a legal claim accusing Apple of secretly slowing the performance of older phones.

The claim, filed in the UK, alleges the company misled users over an upgrade that it said would enhance performance but, in fact, slowed phones down.

The models at issue are the iPhone 6, 6 Plus, 6S, 6S Plus, SE, 7, 7 Plus, 8, 8 Plus and iPhone X models.