The companies, announcing the sale in separate statements on Friday, did not disclose the price but the Financial Times, citing unnamed sources, said the deal would be valued at 1.8 billion euros (1.5 billion pounds). Mehilainen had sales of 756 million euros last year.

The Finnish healthcare industry is restructuring ahead of a potential shake-up aimed at boosting competition between healthcare providers by opening up more opportunities to the private sector.

Mehilainen said CVC would buy a stake of around 50 percent and Finnish insurance group Lahitapiola and pension funds Varma and Ilmarinen would increase their stakes to more than 30 percent combined. The actual stakes will be announced when the deal has closed.

"This is a very good solution. A stock market listing would have been an option, but this is better at this stage as the market is in transformation," Mehilainen's CEO Janne-Olli Jarvenpaa told Reuters by phone. "We'll have a long-term investor with capability to fund growth projects."

He declined to disclose the price of the deal and CVC, KKR and Triton were not immediately available to comment.

The Finnish parliament is expected to vote on the government's healthcare reform bill next month.

On Thursday, Mehilainen's rival Terveystalo agreed to buy Swedish rival Attendo's Finnish operations for 233 million euros.

(Reporting by Jussi Rosendahl; Editing by Susan Fenton)