Paul Tucker, the deputy governor of the Bank of England, will face MPs to discover if he was involved in the Libor scandal that hit Barclays.
The Treasury Select Committee will have the chance to question the deputy governer, to try to discover if he had a role in the process that led to the Libor rate being fixed at an artificially low level.
Former chief executive Bob Diamond, who was forced to resign over the scandal, said that he had spoken with Tucker in 2008 over Barclays' Libor rate.
In notes released last week by Diamond, it seemed to suggest that Tucker had suggested that the government said that Barclays' Libor rate was too high. In the weeks that followed the bank's rate fell.
However Diamond denied that the phonecall in 2008 was an instruction to lower the rates.
But Mr Diamond's account of the conversation ultimately led to the then president of investment banking arm Barclays Capital, Jerry del Missier, telling staff to submit lower Libor.
Barclays have already been fined £290m over the scandal.