PARIS, June 12 (Reuters) - L'Oreal, maker of brands like Lancome and Maybelline, said on Tuesday it would seek to appeal a British court ruling favouring a U.S. start-up that accuses the French cosmetics giant of infringing its patent on a haircare product.
The case is one offshoot of a long-running row that has also sparked litigation in the United States.
Olaplex, a firm based in California, argues L'Oreal infringed the UK patent for its "Bond Multiplier" products - a treatment mainly for use in salons which protects bleached hair and proved a hit with celebrities such as Kim Kardashian.
L'Oreal, which at one point in mid-2015 was in takeover discussions with Olaplex, later launched a competing product, Smartbond, which the U.S. start-up claims dented its sales.
The French beauty group denies accusations it had access to confidential information during the acquisition talks, and says no formal due diligence that would have given it greater access ever took place.
The UK High Court dismissed 10 out of 11 claims in the case filed by Olaplex, according to its ruling on Monday, but upheld one claim related to the ingredients in Olaplex's formula, marking a setback for L'Oreal.
Judges will later decide whether to grant an injunction against further sales of L'Oreal's Smartbond products, Olaplex said.
L'Oreal said it strongly disagreed with the court decision, adding: "We will be applying for permission to appeal." (Reporting by Sarah White; Editing by Adrian Croft)