Mr Osborne added that the prime minister "hasn't saved this economy and he hasn't even saved the British banks yet".
Liberal Democrat treasury spokesman Vince Cable said the government's latest plans were inadequate, urging instead for the whole banking sector to be nationalised.
"The government must bite the bullet on the public ownership and control of the banks to ensure that lending is maintained to sound companies who can keep the economy ticking over in these turbulent times," he said.
The long list of policies includes a scheme to offer insurance against banks losing more money from the bad debts that started the credit crunch.
Meanwhile, the Bank of England is to be able to buy assets directly from firms.
The government would not reveal how much the latest plan would cost the taxpayer.
Under the insurance scheme, banks will agree with the government the amount they expect to lose from particular debt.
The Treasury will then sell insurance against about 90% of the institutions' additional losses from the debt.
Chancellor Alistair Darling said: "Unless we are prepared to use the power of government to get lending going again then the problems will simply be compounded as more and more firms get into difficulties."
He told the BBC that banks taking out the insurance would have to make "very specific legally binding agreements to lend more money".
Under the Bank of England's new role, it will be able to buy up to £50bn of high quality assets, such as bonds and loans, directly from companies.
Vince Cable believes the government is not addressing the situation correctly.
Northern Rock extension
There have also been changes to the terms of previous bank rescues.
The government has given Northern Rock longer to repay its loans from the government.
There was concern that the timetable for repaying the loans was forcing Northern Rock to reduce its mortgage lending too quickly.
Separately, RBS said it had agreed with the Treasury to swap the £5bn of preference shares the government holds for new ordinary shares, increasing the government's stake from 58% to nearly 70%.
The swap will reduce RBS's annual payments to the government as preference shares have a higher guaranteed rate of return than ordinary shares.
An earlier version of this story implied there was a direct link between the announcement of the government plan and the sharp drop in the price of banking stocks. However we changed the wording of the story, because such a firm correlation cannot be established.
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