Apple has come under pressure to scrap its controversial policy of permanently disabling repaired iPhone 6s when software is upgraded, following a global consumer backlash and claims the company could be acting illegally.

At least one firm of US lawyers said it hopes to bring a class action against the technology giant on behalf of victims whose £500 phones have been rendered worthless by an Apple software upgrade.

In the UK, a barrister told the Guardian that Apple’s “reckless” policy of effectively killing people’s iPhones following the software upgrade could potentially be viewed as an offence under the Criminal Damage Act 1971. The act makes it an offence to intentionally destroy the property of another.

The Guardian revealed on Friday how thousands of iPhone 6 users found an iOS software upgrade permanently disabled their phone, which was left displaying an “Error 53” code. Nothing could be done to restore it to working order.

The Apple iOS 9 software update which it launched last autumn will, in the jargon, “brick” the handset if it detects that the touch ID fingerprint recognition and/or the home button is not the original. Some victims had had their phones repaired by third-party contractors. Others had simply damaged their handset. In most cases the phone had been working normally for weeks or months before the software upgrade shut down the handset.

Apple has described this as a security feature, but some have suggested the policy could be designed to increase revenues by forcing anyone needing a repair to their home button to pay the £236 the company charges in the UK. People whose phones have been shut down and have complained at Apple stores have been told that nothing can be done and they must buy a new handset.

Within hours of publication of the Guardian story, the Seattle-based law firm PCVA called for victims to get in touch, with a view to bringing a class action suit.

Consumers have reacted with disbelief and growing anger.

“Show me where, in consumer law, the vendor has the right to render inoperable the hardware you just bought,” said one poster on the Guardian’s website.

PCVA said it believed Apple’s stance may violate various consumer protection laws in the US, and is offering to represent victims for free.

“We believe Apple may be intentionally forcing users to use their repair services, which cost much more than most third-party repair shops. There is incentive for Apple to keep end users from finding alternative methods to fix their products. Think of it this way: let’s say you bought a car, and had your alternator replaced by a local mechanic. Under Apple’s strategy, your car would no longer start because you didn’t bring it to an official dealership. They intentionally disable your car because you tried to fix it yourself. That is wrong,” it states on its website.

London-based barrister Richard Colbey, of Lamb Chambers, said it was likely that Apple’s actions breached basic consumer laws in the UK, and added that it could be committing an offence under the Criminal Damage Act 1971.

“It is hard to see how something which ceases to work in this way could be said to be of reasonable quality, one of the determinants of which is durability,” he said. The law states: “A person who without lawful excuse destroys or damages any property belonging to another intending to destroy or damage any such property or being reckless as to whether any such property would be destroyed or damaged shall be guilty of an offence.”

If Apple continues with this policy, it could find itself fighting multiple legal battles. It may also face additional scrutiny by the European commission, which is already looking at how it and other big multinational tech firms manage their tax affairs.

Apple has so far declined to comment other than a revised statement issued on Saturday saying: “This security measure is necessary to protect your device and prevent a fraudulent Touch ID sensor from being used. If a customer encounters Error 53, we encourage them to contact Apple Support.”