Nearly 30 million people in the UK who bought an Apple or Samsung smartphone between 2015 and 2024 may be entitled to about £17 if the consumer campaign group Which? is successful in a case against US tech giant Qualcomm.

The consumer group is taking the tech giant to the Competition Appeal Tribunal in London on Monday.

The trial between Which? and Qualcomm is expected to last five weeks. The consumer group is accusing the chip company of anti-competitive practices.

It claims the firm forced Apple and Samsung to pay inflated prices and licensing fees for essential handset components, which then pushed up the cost of those smartphones for consumers.

The BBC has reached out to Qualcomm for comment.

The trial starting on Monday will focus on whether Qualcomm held market power and, if so, whether it abused a dominant position.

If Which? is successful, there will be a second stage seeking £480m from Qualcomm, to be distributed among an estimated 29 million British phone owners affected.

But it could be years until this second stage concludes.

"We filed this claim back in 2021, so this first trial being now in 2025 - it's obviously a bit of a slog," senior Which? lawyer Lisa Webb told the Today programme.

"But the real benefit of this system is that as a consumer, you don't need to do anything... if we win, we will get you your money."

The consumer group is seeking damages for all affected Apple and Samsung smartphones purchased between 1 October 2015 and 9 January 2024.

It says this would probably work out at around £17 per handset. Qualcomm has previously said the case has "no basis".

A similar case against Qualcomm is ongoing in Canada, and the firm has also previously been fined by the EU for antitrust.

Anabel Hoult, chief executive of Which?, said: "This trial is a huge moment. It shows how the power of consumers - backed by Which? - can be used to hold the biggest companies to account if they abuse their dominant position."

Qualcomm is one of the world's biggest producers of smartphone chips and has faced allegations about anti-competitive behaviour before.

The Federal Trade Commission in the United States sued the firm for unfair practices in the way it licensed its technology back in 2017, but had its case dismissed in 2020.