HSBC is to lose two board directors at its UK unit amid a toughening of Britain’s rules around bank officials’ accountability, a person familiar with the matter said Tuesday.

HSBC Bank board member Alan Thomson has submitted his resignation, the person said, after holding the post since April 2013. He was a member of the unit's audit and risk committees, and holds several other directorships at non-financial UK companies. The UK bank's deputy chairman, John Trueman, is also expected to resign, the person familiar with the matter said. Trueman has been a director at the bank since 2004 and started his current role in December. He is also chairman of HSBC Private Bank UK, according to HSBC's annual report.