LONDON ( TheStreet) -- HSBC's ( HBC) Chairman Stephen Green is stepping down from his role to fulfill the role of U.K.'s Trade Minister, U.K.'s largest bank said Tuesday.

The 61 year old Green begins his new governmental role in January, HSBC said in a release.

Green is a 28-year veteran and longtime executive to HSBC. He has been chairman of HSBC's holding company since 2006. He was HSBC's Group CEO from 2003 to 2006, which was then handed off to its current CEO Michael Geoghegan. Green joined HSBC in 1982 and became an executive director in 1998.

HSBC has not named a successor but said that its non-executive directors had already been working on Green's succession for several months, including appointing external advisers. The bank added that it was always the board's intention to approve a successor to Green before the end of the year. That timetable remains on schedule, it says.

Green's departure comes as the U.K's third largest bank, Barclays ( BCS), announces its own succession plan in which U.S-born Robert Diamond will become group chief executive succeeding John Varley, who is retiring in March 2011. Diamond, who heads the bank's corporate and investment banking unit and the Barclays Wealth business, will assume the title of president and deputy group CEO on Oct. 1, 2010. He has been a member of the board since 1995.

HSBC struggled against the financial crisis as it took grip in the U.S., where HSBC has a solid franchise. The London-based bank has been looking to dispose of U.S. assets including its consumer finance and mortgage arms across the Atlantic.

Green said in a statement that he would leave the company "in the safe hands of the most talented executive team in banking. It is a tribute to them and to my colleagues around the world that HSBC is in such good shape, as the world's largest independent bank."

HSBC shares were flat at roughly 11:30 am ET. Shares of Barclays sank 5.2%, amid fresh concerns about the European banks' health.

--Written by Laurie Kulikowski in New York.

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