Seven & i Holdings says it has received a new acquisition proposal from a major Canadian convenience store operator. The Japanese retail giant is expected to review the offer in a special committee of only outside directors.

Seven & i has not disclosed any details about the proposal. But sources say Alimentation Couche-Tard raised its offer by about 20 percent to 47.2 billion dollars.

Seven & i says it received a "revised confidential, private and non-binding proposal".

Sources say the Canadian operator of Circle K convenience stores made the new bid on September 19.

The previous proposal was about 39 billion dollars. Seven & i rejected that offer on September 6, saying it "grossly undervalues" the Japanese firm.

Seven & i also expressed reservations at the time about a deal even at a higher price. The firm said a merger would face scrutiny from US regulators.

The company's 7-Eleven brand makes up the biggest convenience store chain in the US, while Couche Tard's Circle K is number 2.