Wal-Mart has taken a controlling stake in Tokyo-based supermarket chain Seiyu following its its initial move into the country last March.

The US retailing giant will invest 52bn yen ($420m) to increase its share from 6.1% to 34% on December 27.

Wal-Mart gained an option under the March agreement to raise its stake in Seiyu to 66.7% by the end of 2007.