Chancellor George Osborne has called the manipulation of LIBOR rates by Barclays traders "a shocking indictment" of the greed of the financial sector.
The bank was fined a total of £290m yesterday, including a record £59.5m from the FSA.
Speaking in the House of Commons, Osborne said the manipulation highlighted "systematic greed at the expense of financial stability - and the Government at the time were clueless about what was going on."
There were three questioned still to be answered, the Chancellor said: how were such failures allowed to continue unchecked; what changes are needed in the regulatory system in the future; and what further sanctions are needed at Barclays specifically.
The Financial Services Bill will create "a far tougher regulatory system", with the Financial Conduct Authority in particular focussing "razor-like" on market abuse.
But Osborne said it was worrying the FSA had no criminal powers.
On Bob Diamond, who was forced to forfeit his bonus after the fine, Osborne said the Barclays CEO "has some very serious questions to answer, what did he know and when did he know it, who else knew and who should pay the price. We all want to hear his answers."
Shares in the bank fell 16% as of 1pm, with other banks also suffering the possibility of further investigation. The Royal Bank of Scotland was down nearly 13%, with HSBC falling 4%.
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