Prime Minister Kevin Rudd has called on Australia's big banks to help unfreeze investment funds by buying their securities.

Speaking at the Business Council of Australia annual dinner in Sydney tonight, Mr Rudd said the banks could play an important role in freeing up billions of dollars worth of frozen investments.

``Larger and more liquid institutions - including the major banks - could provide liquidity to various market-linked investment vehicles within the financial system by buying their securities at market prices,'' Mr Rudd said.

Australia's banks had performed responsibly during the global financial crisis, he said.

``The banks are the beneficiaries of banking licences, and the government's guarantee on deposits and wholesale funding,'' he said.

``It is not unreasonable, therefore, to expect that the banks will play a continuing role in supporting the wider financial system and thus the Australian national interest.''

The government had asked Future Fund Chairman David Murray to assist Treasury in its talks with relevant financial institutions on this matter, Mr Rudd said.

``As I have previously indicated, the government will continue to respond in a calm, measured and methodical way to deal with the challenges that will continue to emerge in this sector in the future.''

AAP