Adobe has apologised after an update to its Lightroom app permanently deleted years of photos on iPhone, iPad, and iPod Touch users' devices.

The issue was caused by an update to the Lightroom app on iOS, which is used to organise and edit pictures without changing the original - something which the image editor on iOS doesn't do.

Ironically, users who were using the app to preserve their original images have now found those pictures to be permanently deleted, with no mechanism for recovering them.

Although the bug has now been fixed, many users who had downloaded the Lightroom app - and who hadn't saved their photos to the Lightroom cloud - have lost their pictures.

Versions of the app on Android devices were not affected by the bug, and back-ups are also unaffected, but users who stored all of their pictures on their devices are out of luck.

On social media site Reddit, users are mourning the loss of their images, including one who said that more than two years' worth of photographs and edits were unrecoverable.

"I've talked with customer service for four plus hours over the past two days and just a minute ago they told me that the issue has no fix and that these lost photos are unrecoverable," they wrote.

In a statement, an Adobe representative said: "We are aware that some customers who updated to Lightroom 5.4.0 on iPhone and iPad may be missing photos and presets that were not synced to the Lightroom cloud.

"A new version of Lightroom mobile (5.4.1) for iOS and iPadOS has now been released that prevents this issue from affecting additional customers.

"Installing version 5.4.1 will not restore missing photos or presets for customers affected by the problem introduced in 5.4.0."

The spokesperson added: "We know that some customers have photos and presets that are not recoverable.

"We sincerely apologise to any customers who have been affected by this issue."