Private equity firms Cinven and Advent have teamed up to bid in an auction that could value Nestle's skin health business at about 7 billion Swiss francs ($7 billion), three sources familiar with the matter said.

Private equity companies Blackstone, KKR, Carlyle, CVC, EQT and Partners Group are also expected to bid and might look for partners, according to the sources, who declined to be identified as the process is private.

Nestle launched a review of the unit in September, as the maker of Nescafe coffee and Perrier water ditches underperforming businesses and fends off criticism from an activist investor who wants an overhaul.

The fragmented consumer health sector is attractive for deals because of aging populations in many industrialised nations, increased interest in health and rising incomes, analysts say.

Information memorandums on the skin health business sale, being run by Credit Suisse and Evercore, are expected to be sent by the end of January and first-round bids are likely to be submitted in early March, the sources said.

Nestle and all the funds declined to comment.

Merz Pharma, a private German company that sells wrinkle fillers and other skin treatments, has reached out to several private equity bidders to find a partner, the sources said.

The move by Merz shows the strength of private equity in the auction, given they want the whole Nestle unit. Industry rivals are only expected to bid for parts of the business.

Nestle Skin Health, which sells Cetaphil and Proactiv skin care products, Restylane wrinkle fillers and prescription dermatology medicines, had sales of 2.7 billion Swiss francs last year, accounting for about 3 percent of Nestle's total.

The sources said industry players which might take part in the auction included Beiersdorf, Allergan, Henkel, Johnson & Johnson (J&J), L'Oreal, Pfizer and Unilever.

They all declined to comment as well.

Sources previously estimated the unit could fetch 6 billion to 8 billion francs.

On Monday, one source put the range at 7.5 billion to 8.5 billion francs, based on 2018 operating earnings of 500 million to 550 million francs. Another source said the price tag could reach more than 9 billion francs if the unit was broken up.

Nestle, the world's largest packaged food maker, created the Skin Health unit in 2014 when it bought out L'Oreal's stake in their Galderma joint venture.

Under CEO Paul Bulcke, skin treatments were part of Nestle's push into higher-growth health products to counter a slowdown in its traditional food business. But the unit has performed poorly, leading to one-off costs and restructuring.