Sumitomo Mitsui Banking Corp. said Wednesday that it will invest an additional ¥35 billion in Bank of East Asia, becoming the third-largest shareholder in the Hong Kong-based major commercial bank.

SMBC, a core unit of Sumitomo Mitsui Financial Group Inc., is cementing its ties with the bank that runs more than 100 offices in mainland China to gain expertise in retail banking and services for smaller businesses in the country.

SMBC's equity stake in Bank of East Asia will rise to 9.50 percent from 4.73 percent after the Japanese bank buys new shares to be issued by the bank this month.

SMBC first bought into Bank of East Asia in 2010 after forging a partnership in 2008 to enable access to each other's customer base and cooperate in fundraising in local currencies.