Apple is facing legal action from a group of 27,000 South Koreans after it was revealed their iPhones had been storing data about the handset's location.

In April this year, two security researchers, Pete Warden and Alasdair Allan, revealed the practice at the Where 2.0 conference in San Francisco.

They stated that the iPhone logs the latitude and longitude of its whereabouts at regular intervals - as well as a timestamp - and then saves it to a file on the device. This file is shared with a Mac or Windows PC every time the handset is synced.

The research also warned that by using a simple program the data can be retrieved, meaning that anyone who had access to the iPhone could tell where the owner had been - and when - quite easily.

In May, Kim Hyeong-seok, successfully bought legal action against Apple for the practice and was one million won (£565) in compensation. As a result he is now acting on behalf of the 27,000 South Koreans also seeking the same amount in compensation in the class-action lawsuit

"I'm an iPhone user myself, so when I first heard about this in the media, I reviewed the legality of the matter based on Korean law," Hyeong-seok told Bloomberg.

"I concluded it was clearly illegal."

Hyeong-seok expects the first hearing in the lawsuit to take place by November and if everyone is successful in their claim, Apple could end up forking out around $27.6m (£15.6m).

Apple initially disputed the location-tracking allegation, saying that it simply maintains a database of regional cell towers and Wi-Fi access points to improve its phones' location services. However it admitted there were software bugs affecting the system and later issued a software update that limited the amount of Wi-Fi hotspot and cell tower location data stored as well as deleting the data if a user turned of location services.

Apple has refused to comment on the issue.