Nestlé is facing the prospect of rivals copying the shape of its popular four-finger KitKat chocolate bar after European Court of Justice (ECJ) rejected the group’s attempt to secure a trademark for the product in the UK.

Europeans judges ruled this week that the KitKat’s shape was not distinctive enough to be exclusively used by Nestlé. The company was not seeking to trademark the two-fingered version of the product.

Nestlé has argued that, over time, the four-fingered chocolate bar's physical form had acquired a distinctive character associated with the company since its launch in 1935, and should become a trademark to prevent competitors making rival chocolate bars of the same size and shape.

The decision follows a ruling back in June by the Advocate General of the European court of justice, whose opinions are usually followed by the ECJ, who said Nestlé’s attempts to trademark the KitKat shape did not comply with EU law. The Advocate General had said a 3D shape can be registered but only if it alone has acquired distinctiveness. It would not be enough if the 3D shape was distinct only when in combination with a brand name or packaging.

A final ruling on whether rivals can launch copycat KitKats in the UK will now be made by the UK High Court. The UK court had already rejected Nestlé’s trademark application in 2013 amid opposition to the move from rival Cadbury. The two firms have been engaged in 10-year battle, fought in the courts, which started when Cadbury tried to trademark the purple colour it uses on its Cadbury chocolate wrappers. Nestlé objected and finally had the original decision allowing Cadbury to trademark the colour overturned in 2013.

The Kitkat brand generates sales of around £40m for Nestlé in the UK and intellectual property lawyers said the firm is likely to continue arguing its case to protect it business.