CMS UK is being sued for negligence by three parties including Alexander Mayr, a former director of Spokane, a Swiss private equity holding company owned by the Swarovski family.

The claim, which was filed in the Queen's Bench Division of the High Court earlier this year, concerns advice given by former CMS international private equity head Ted Cominos and former associates John Faurescu and Cristina Proca.

The claim form, filed in January this year, states that the claimants – which also include Rouver Investments, a Luxembourg company wholly owned by Mayr, and Life Science Partners, a now-dissolved investment advisory company also controlled by Mayr – are seeking damages for "breaches of contract, negligence, breaches of fiduciary duty and breaches of confidence".

It states that they expect to recover more than £100,000, and that their "current best estimate" is that the value of the claim is in excess of £65m.

The claimants are being advised by Asserson Law Offices, a UK law firm based primarily in Tel Aviv, while CMS has turned to Simmons & Simmons.

The particulars of the claim, filed on 26 January, centre around two transactions in 2011 – Mayr's acquisition of the Laboratoires Mitry-Mory (LMM) pharmaceutical plant from biopharma company Cephalon for the nominal price of €1; and Spokane's subsequent acquisition of an 8.5% stake in LMM for €3.5m.

The dispute focuses on the question of what Mayr disclosed – and was obliged to disclose – with regards to the former deal, on which CMS advised.

The claimants say the value of the plant was more than €50m, but that Cephalon wanted to sell it off because the costs of winding it down would have been higher.

The particulars of the claim set out the case that CMS "failed to advise" Mayr in respect of his potential duties as a director of Spokane and his disclosure obligations. The claim states: "At no time… did Faurescu, Cominos or anyone else at CMS mention, let alone advise, in relation to Mayr's potential duties or obligations as a director of Spokane… Throughout this period, Mr Mayr considered that he had acted at all times in accordance with CMS's advice, and CMS had not given him cause to believe otherwise."

Asserson senior partner Trevor Asserson commented: "The core allegation in this case is that CMS took steps to distance itself from its own client, Mr Mayr, and then, in breach of its professional obligations and using client confidential information, orchestrated a series of claims against him, destroying his ability to function as a business owner and manager."

CMS denies it has any liability to the claimants, and in its defence, argues that the claim "arises from the fraud of the claimants".

The defence states: "The fraud was obtaining €3.5m from Spokane for an 8.5% share of LMM, which only held the Mitry-Mory Plant he [Mayr] purchased for €1, while deliberately misrepresenting and avoiding disclosing the true position to [Spokane board chairman] Mr Werner and Spokane, and misrepresenting to CMS what he had told Mr Werner and Spokane."

Cominos, Faurescu and Proca all worked together at Linklaters during the 2000s before reuniting at CMS.

In 2012, Cominos and Proca left to join US firm Edwards Wildman, which subsequently merged with Locke Lord. The duo joined Faegre Baker Daniels in February last year. According to his LinkedIn page, Faurescu is now a senior counsel at Impax Laboratories in California.

A court hearing is scheduled for the end of July.