Staples, which is in the process of going private, received an offer of $625 million to $700 million for its more than 1,200 retail stores and brand, according to a company filing with the Securities and Exchange Commission.

The report has some industry observers saying that the would-be buyer must be Boca Raton-based Office Depot, which tried to merge with Staples last year but called it off after a challenge by the Federal Trade Commission.

Office Depot had no comment Monday on the speculation, said AnneMarie Matthews, spokeswoman for the office supply retailer. Staples didn’t immediately respond to a request for comment.

Staples says in its July 21 filing that on June 5, “Party A submitted a non-binding proposal to acquire the company’s U.S. retail business for $625 million to $700 million in cash.”

If Office Depot is allowed to buy Staples’ stores, it would “be a backdoor way of getting the…