National Australia Bank chief executive Andrew Thorburn will take extended period of leave from the bank after a bruising year of scandals at the big four lender that ran as deep as his own office, that he described as "the biggest and most relentless" of his career.

A spokesman for the bank confirmed that Mr Thorburn is taking holidays following the annual general meeting this week, and will return to work ahead of the release of the Hayne royal commission's final report, which is due on February 1.