The watchdog alleges that SMBC Nikko, the brokerage unit of Sumitomo Mitsui Financial Group Inc, bought five individual stocks on the market to push up their prices so that block trade deals for those stocks would not fall through.

SMBC Nikko said it apologized for causing concern and pledged to work with the watchdog.

The fresh charges come after the brokerage house and five of its former executives were indicted last month for similar alleged market manipulation of different stocks.

(Reporting by Makiko Yamazaki; Editing by Ed Osmond and Alexander Smith)