The chairman of the Federal Reserve, Ben Bernanke, has signal that the US central bank will not take any immediate action to boost growth. In a keenly anticipated speech, Mr. Bernanke simply said the Fed had a range of tools that could be used to provide additional monetary stimulus and their use would be considered at an extended meeting in September.Mr Bernanke also hinted that the US government needed to do more to aid economic growth. Earlier, revised data showed the US economy grew less than first estimated in the second quarter of 2011.The Commerce Department now says the economy expanded at an annualised rate of 1 per cent between April and March, down from its first estimate of 1.3 per cent.The figures were seen as raising pressure on the Federal Reserve to do more to boost the economy, for instance by introducing further quantitative easing an injection of cash into the financial system.