The chief executive of Poland's Bank Millennium SA (MIL.WA), Boguslaw Kott, will leave the bank's top job by June 2013 after heading the lender since 1989, Millennium said Tuesday.

Millennium's troubled owner, Banco Comercial Portugues S/A (BCP.LB), had put its Polish unit up for sale last year because of a heavy debt load, but dropped the plan after restructuring its balance sheet.

"Until [July 1, 2013] Mr. Boguslaw Kott will remain the chief executive of Millennium Bank for time needed to prepare and implement new solutions related to strategic management and development of Millennium," the bank said in a statement.

After stepping down, Kott will have the option of joining the bank's supervisory board.

-By Patryk Wasilewski; Dow Jones Newswires; +48 22 447 2430; patryk.wasilewski@dowjones.com