MUFG, Japan's largest bank, had said last week that it would launch a tender offer for the 35 percent it does not already own in UnionBanCal at $63 for each share but the offer was dismissed by the California bank as too low.

MUFG said it would brief on its bid for UnionBanCal at 0800 GMT (4 a.m. EDT).

(Reporting by David Dolan)