High street fashion chain Forever 21 is being sued by Adobe for allegedly using pirated copies of Photoshop.

The company could face a large fine if a court finds in favor of Adobe, which says the chain used the copies of Photoshop “even after being contacted by Adobe regarding the infringement”.

The detailed lawsuit was filed this week and includes the registration numbers of the software products involved, plus dates on which the software was used.

Adobe says it is a case of “willful, intentional and malicious copyright infringement” and is asking the court to issue an injunction and award a cash sum for lost revenue, court costs and additional damages.

It is unclear how Adobe discovered its software was allegedly being wrongly used by Forever 21, but in recent years it has actively encouraged people to turn in employers who are using pirated software.

Adobe says “it would be difficult to ascertain the amount of damages” needed, and that several hearings would be required to establish just how much the company has lost as a result of the breaches.

The case was filed in California and also alleges that Forever 21 – which has revenues of around $3.9 billion – copied 3D design software Autodesk and zip utility tool WinZip.

Sky News has contacted Forever 21 for comment.