A special committee of 7-Eleven's ( SE - Get Report) board rejected a buyout offer that sent the convenience chain's stock up more than 20% earlier this month.

The committee, formed after 7-Eleven's Japanese parent offered to buy out the U.S. company's public owners at $32.50 a share, said the price is "inadequate" and "not in the best interest of the shareholders." It urged shareholders to reject an ongoing tender offer.

"The special committee instructed its financial and legal advisers to contact 7-Eleven Japan's financial and legal advisers to commence discussions regarding an increase in the tender offer price," the company said. "These discussions have commenced; however, there can be no assurance as to when or if such discussions will result in an increase in the tender offer price by 7-Eleven Japan."

The Japanese company already owns about 73% of 7-Eleven's outstanding stock. It has already begun tendering for the rest as part of an offer that could total about $1 billion.

Seven-11's stock closed Wednesday at $35.54.