Frowns in the tech sector after Apple admitted it's been slowing down older iPhone models, every time users get a software update.

The company says it's being done to save the phones' batteries, which slowly degrade over time.

Some customers believe it's a sly trick, to get people to upgrade to an expensive new phone.

But Apple said it's all about the batteries.

Technology correspondent Peter Griffin said it's a clear example of consumers being misled.

"It's actually quite staggering in scope, that they've apologised for something that they did deliberately, that it wasn't a mistake that they are owning up to and they're rectifying it with big discounts on batteries."

Griffin said the situation has been made worse because Apple only confessed after it was caught red-handed in tests.

"Partly that's the massive price of that phone, it's very expensive, but also I think there will be some impact on trust where a lot of people say well I'm out because effectively you deceived me."

He said planned shipments of the new iPhone X have been dialled back for 2018.