Mark Carney, who is also governor of the Bank of Canada, said the FSB had made progress in implementing reforms to ensure no bank was considered "too big to fail," but that more work may need to be done.

"It is not clear yet that too-big-to-fail has been ended. For example, credit-rating agencies continue to boost their ratings of major banks by a factor that recognizes implied government support," Carney said in remarks prepared for a speech in Montreal.

"Despite the proclamations of G20 leaders, investors seem to think governments will once again blink when faced with a failing large bank," he said, adding this might "underscore the need for further measures."

The FSB, the regulatory task force of the Group of 20 leading economies, has identified 28 global banks that will be subject to special rules because they are so big and complex that they could drag down the entire financial system if they fail.

The rules are part of a series of reforms that form the world's response to the global financial crisis. They range from bolstering bank capital to regulating the so-called shadow banking sector, a parallel credit system covering money market funds, special investment vehicles, hedge funds and repurchase agreements.

Because of the changes, the world's banks are now safer than they were on the eve of the crisis, Carney said.

"While much has been accomplished, much more needs to be done," he added.

Carney made no mention of domestic monetary policy or the Canadian dollar in his speech.

Canada's central bank has held its key interest rate at 1.0 percent for over two years. It has signaled since April that its next move will be to hike rates rather than lower them, but last month Carney said such a move was "less imminent."

Carney is scheduled to give a press conference at 2 p.m. (1900 GMT) on Thursday.