Boulder-based natural foods grocer Wild Oats Market Incorporated says federal regulators will file a lawsuit to prevent its acquisition by competitor Whole Foods Market Incorporated.

But Wild Oats' chairman and Chief Executive Officer Greg Mays says his company and Whole Foods will challenge any lawsuit that's filed, because they believe the merger will benefit the marketplace.

FTC spokesman Mitch Katz says the agency has no comment.

Whole Foods has said the FTC is considering trying to prevent the sale from being completed over concerns over anticompetitive effects.

Austin, Texas-based Whole Foods offered in February to acquire Wild Oats for about $565 million dollars.

It would also assume about $106 million dollars in debt as part of the deal.