The firm took control of Biomnis after handing over €217 million (£172.7 million) and has announced that it will support the company’s expansion plans.

The deal was completed with the help of senior debt arranged by Fortis and mezzanine finance authorised by AXA Mezzanine.

Post-completion, Pierre-Yves Guiavarch from healthcare services group General de Sante joins Biomnis as chief executive, replacing Jean-Louis Oger who becomes non-executive chairman. Duke Street partners Charles Woler and Thierry Paternot have also joined the board as non-executive directors.

Duke Street’s previous deals in the healthcare market include dentistry group Oasis Healthcare, psychiatric hospitals operator Affinity and Paris-based hospital operator Groupe Proclif.

Founded in 1897, Biomnis, formerly Laboratoire Marcel Mérieux, provides pathological analysis, primarily in molecular diagnostics, tissue, fertility treatment and specialised biochemistry. It has revenues of more than €220 million (£175.3 million) and some 1,600 staff.

It is also a service provider to laboratories throughout France, operating from Paris and Lyon, with further sites in Dublin and Dubai. The group owns TSE, a logistics operation handling five million samples a year.