The chairman of Barclays bank will face MPs on the Treasury Select Committee on Thursday - a hearing that is expected to go ahead irrespective of his decision to quit.
Marcus Agius will announce his resignation at 7am today after informing fellow board members of his decision yesterday, according to reports.
Bob Diamond tonight angrily rejected suggestions that he misled MPs over regulators' concerns about activities at Barclays.
The Bank of England's Paul Tucker told MPs he refuted claims that he attempted to influence Barclays into manipulating the Libor rate.
MPs will be hoping the Deputy Governor of the Bank of England will shed some light on unanswered questions about rate-fixing at Barclays.