Technology giant Apple is facing a £768m collective action over claims it secretly ‘throttled’ iPhones with software updates to disguise overloaded batteries.

Consumer champion Justin Gutmann, formerly of Citizens Advice, is bringing the case on behalf of around 25 million people against Apple for allegedly abusing its market dominance by concealing a ‘power management tool’ in updates which reduced iPhones’ performance by up to 58%.

The opt-out claim, which is being brought in the Competition Appeal Tribunal, contends that Apple introduced the tool because iPhone batteries were unable to cope with new software which caused sudden shutdowns.

Gutmann – who was last year certified to act as class representative in collective proceedings against three train operators for allegedly overcharging passengers – said: ‘Instead of doing the honourable and legal thing by their customers and offering a free replacement, repair service or compensation, Apple instead misled people by concealing a tool in software updates that slowed their devices by up to 58%.

‘I’m launching this case so that millions of iPhone users across the UK will receive redress for the harm suffered by Apple’s actions. If this case is successful, I hope dominant companies will re-evaluate their business models and refrain from this kind of conduct.’

His solicitor Rodger Burnett, director of London litigation firm Charles Lyndon, said: ‘Apple has millions of loyal customers in the UK but in this instance they breached the trust placed in them by their customers by not being open and transparent which led to software being installed on iPhones which made them significantly less valuable.’

Apple, which also faces a £1.5bn collective action in the CAT over allegedly abusive conduct in relation to software app distribution and payment processing services on certain devices provided via the App Store, said in a statement: ‘We have never – and would never – do anything to intentionally shorten the life of any Apple product, or degrade the user experience to drive customer upgrades.

‘Our goal has always been to create products that our customers love and making iPhones last as long as possible is an important part of that.’