Alistair Darling today urged the banks to improve lending to businesses, saying he was "extremely concerned" about the cost of borrowing.
Bank chiefs are to be hauled in to meetings with the Government to explain why they are charging more for credit when interest rates are at historically low levels.
The Chancellor suggested they had failed to keep promises to improve lending facilities in return for massive taxpayer support.
Warning bankers they had not been rescued as "some sort of charitable act", he went on: "We did it because if you don't have a banking system that creates credit for businesses then you will make recovery and prosperity after that much more difficult."
Speaking on BBC1's Andrew Marr Show, he said: "I am extremely concerned at what the banks are doing for the small and medium sized businesses in this country
"What companies are being charged does seem to have gone up relative to what banks are actually having to pay because of the fact we have got very low interest rates."
Mr Darling acknowledged that the banks needed to re-build their balance sheets in the aftermath of the financial crisis.
But he added: "At the same time, because of the particular circumstances we are in now, because of the fact we've got this recession, we also need them to lend money and that's why we recapitalised them to do that.
"That means they've got to live up to the promises they've made.
"That's why we will be going through with each individual bank asking them why is it, at a time when the cost of borrowing is coming down, it would appear that the cost to small business appears to have gone up?
"We're playing our part, the banks have got to understand that the public will not understand it if they do not play their part to the full."