TOKYO (Reuters) - Japan's Seven & i Holdings ( SVNDF ), operator of the 7-Eleven convenience store chain, has picked Bain Capital as its preferred buyer for a stake of its non-core assets, local media reported on Saturday.

Bain has been competing against rival private equity firm KKR and local buyout firm Japan Industrial Partners in bidding since late last year for a major stake in York Holdings, an entity that the retailer plans to spin off.

Bain is believed to have offered a valuation of more than 700 billion yen ($4.7 billion) for York Holdings, the Nikkei newspaper and Jiji news agency reported. Nikkei cited a person it did not name, while Jiji did not specify where it received the information.

Seven & i ( SVNDF ), KKR and Japan Industrial Partners could not be immediately reached for comment on Saturday, while Bain said it could not comment.

The retailer has sought to separate non-core businesses that include its supermarket operations into York Holdings. The unit will house 31 subsidiaries including the group's superstores business, baby goods store Akachan Honpo and the company that operates Denny's restaurants in Japan.

($1 = 149.2900 yen)