Major trading house Marubeni Corp. is buying more shares of Maruetsu Inc., a supermarket-chain unit of ailing retailer Daiei Inc., to raise its stake to 25.2 percent by October from 24.2 percent, Marubeni officials said Thursday.

The move is part of Marubeni's plan to extend its reach into the retail business, they said.

The Marubeni group has been raising its share in Maruetsu since November by buying up shares from Maruetsu's other stockholders, including banks and insurance companies. It had a 20 percent stake at the end of March.

The group is estimated to have spent 2 billion yen to 2.5 billion yen buying additional Maruetsu shares since April, according to industry officials.

The Marubeni group is currently Maruetsu's second-largest shareholder next to the Daiei group, which has a 35.5 percent stake.