Bank of England governor Mervyn King can expect tough questioning over his handling of the Northern Rock crisis when he appears before a panel of MPs.
He is under pressure over the Bank of England's performance in recent weeks.
Members of the House of Commons treasury select committee will quiz him on Thursday over the "credit crunch" taking hold of financial markets.
Mr King will also face questions on his handling of the crisis and emergency funding agreed with Northern Rock.
BBC business editor Robert Peston says the possibility that the flight of capital from Northern Rock could have been avoided is "seriously embarassing" for Mr King, one of whose functions is to maintain financial stability.
Our correspondent also told BBC News that the group of biggest banks in the UK were "furious" with Mr King over his handling of recent events, adding: "They felt he did not understand the size of the problem he was grappling with."
On Wednesday the Bank agreed to pump £10bn into money markets to cut rates.
Lending between financial institutions has all but dried up, sending the cost of borrowing even for three months up as banks worry about their counterparts' exposure to the US sub-prime mortgage crisis.
The Bank of England had initially refused to prop up Northern Rock's business after the Newcastle lender found it could no longer access affordable short-term loans in the money markets because of the global credit crisis.
The Bank's view was that a bail out would send wrong signals to the banking sector, encouraging the continuation of risky practices, thus creating a "moral hazard."
However when the Bank then agreed to give emergency financial support to the Northern Rock, one of the UK's largest mortgage lenders, that led to thousands of panicking savers rushing to withdraw their savings.
Only when the government guaranteed their savings did the rush to withdraw money abate, and Mr King is now being criticised for not having acted sooner.
"Tomorrow's Monetary Policy Committee testimony to the Treasury Committee should make for interesting viewing," said Daragh Maher, strategist at Calyon.
And some committee members are already asking questions ahead of the meeting.
"We certainly need to understand from him why the Bank of England has changed its mind," said Michael Fallon, a Conservative member of the committee.
Refusal to intervene
The Bank already moved to prop up overnight markets between banks hit by fears over potential losses on the high-risk US sub-prime mortgages.
But it then refused to intervene in three-month money markets, saying that banks should face the consequences of risky longer-term lending.
That decision was then changed when soaring interest rates hit the money markets.
However, although Prime Minister Gordon Brown has given Mr King his backing, many bankers have been upset with the Bank's actions over the last month, and many on the Treasury committee will have tough questions to ask.
BBC business editor Robert Peston says that what happened at Northern Rock, the first run on a British bank in living memory, has caused deep shame and embarrassment in the banking industry.
And Mr King's refusal to flood the banking system with cash over the past few weeks is being blamed as the cause of the humiliation of their industry, Mr Peston adds.
BBC News 24 will be running a special day of programming looking at the credit crunch, on Thursday, 20 September.