ZURICH, March 28 (Reuters) - UBS Chief Executive Officer Sergio Ermotti is open to extending his time at the helm of the Swiss lender to help oversee the integration of Credit Suisse, according to a letter to published in the bank's annual report on Thursday.

"Sergio has committed to stay at least until the completion of the integration process, if not longer," according to the letter Ermotti and UBS chairman Colm Kelleher sent to shareholders.

Last September, Ermotti said he would remain as CEO until the end of 2026. According to previous guidance, UBS wants by then to have largely completed the integration of its smaller rival, which it acquired last year.

(Reporting by Oliver Hirt)