WASHINGTON (Kyodo) Citigroup Inc. said Wednesday former U.S. Ambassador to Japan Howard Baker will become an adviser on international affairs to its senior management.

"Howard's vast knowledge and experience in international relations, combined with his unique perspective and familiarity with Japan, will be instrumental in helping Citigroup drive the future growth of our unique international franchise," Citigroup CEO Charles Prince said in a statement.

The appointment is in line with Citigroup's ongoing efforts to repair its reputation outside the United States, which has been tarnished since last year.

Japan's financial regulators last September ordered the bank to halt its private banking operations, which cater specifically to wealthy clients, after uncovering manipulative lending practices and failure to screen for suspected money-laundering.

It was also revealed last month that German investigators are looking into Citigroup's unusual bond trading activities on the euro-zone trading platform last August. Italian investigators are expected to follow suit.

Baker served as U.S. ambassador to Japan from 2001 to mid-February this year. He was a Republican senator from Tennessee from 1967 to 1985, and served two terms as majority leader.