Remgro, a major shareholder of South Africa-based private hospital group Mediclinic, is to buy a 29.9% shareholding in FTSE 250 peer Spire Healthcare.Remgro has entered into an agreement to buy the stake from Cinven for 360p per share, equal to £432m. Mediclinc then intends to acquire the holding from Remgro "in the near future".Spire's shares closed Friday's session at 320p, valuing the group at just under £1.3bn.However, Remgro and Mediclinc have both confirmed that the deal does not represent a precursor to a takeover offer for the whole of Spire.Instead, Mediclinic and Spire have agreed to "explore ways in which they can work together"."We welcome Remgro, and in due course Mediclinic, as a new long term shareholder in our business," said Spire chief executive Robert Roger."This is an exceptional opportunity for us to gain a strategic investor who understands our business and growth ambitions as we develop our asset base to meet the significant capacity growth we expect for the UK private healthcare sector in the medium to long term and we look forward to working with them to explore ways our two businesses can co-operate to serve both our patients and our shareholders even more effectively."