Alistair Darling, the chancellor, will on Monday unveil details of the arm’s-length agency that will manage the £37bn ($59bn) in stakes the government agreed with banks to help them in the credit crisis.

The Treasury said the agency’s staff would be tasked with monitoring the lending activities of the banks to ensure that they fulfil the pledge to ensure funding of small businesses and that mortgage borrowers get a fair deal without the banks ramping profit margins at their expense.