Mr Bernanke's comments caused US shares to dip, but they recovered later
The chairman of the Federal Reserve, Ben Bernanke, has signalled 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, he said.
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% between April and March, down from its first estimate of 1.3%.
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.
Mr Bernanke said the central bank's next meeting in September had been extended from one day to two "to allow a fuller discussion" of its next move.
"The Committee will continue to assess the economic outlook in light of incoming information and is prepared to employ its tools as appropriate to promote a stronger economic recovery in a context of price stability," he said.
'Spiral out of control' Speaking at a meeting of central bankers in Jackson Hole, Wyoming, Mr Bernanke suggested that the government could do more on fiscal policy.
"Most of the economic policies that support robust economic growth in the long run are outside the province of the central bank," he said.
The US Fed chief seems to have provoked two reactions.
There was disappointment among those who hoped for an immediate relaunch of the money creation policy known as QE.
Others, meanwhile, latched onto Ben Bernanke's view that longer-run prospects for the US economy were not as bad as some were predicting.
He has left the door open for more QE at the Fed's extra long meeting next month, which will keep the markets guessing.
His call for a "better process for making fiscal decisions" is an intriguing swipe at US politicians. It serves as a rejection of the idea that the Fed can on its own wave a magic wand to conjure up growth in the world's biggest economy.
"To achieve economic and financial stability, US fiscal policy must be placed on a sustainable path that ensures that debt relative to national income is at least stable or, preferably, declining over time.
"As I have emphasised on previous occasions, without significant policy changes, the finances of the federal government will inevitably spiral out of control, risking severe economic and financial damage."
This view was supported by Vincent Reinhart, a former director of the Federal Reserve Board's Division of Monetary Affairs.
"Federal Reserve officials would like nothing more than to be left alone: the basic problem is that if you drew up a list of what could be done out of Washington to try to help economic expansion, Federal Reserve action is pretty low on the list.
"The reason why we have this unhealthy focus on the Federal Reserve is that the politicians aren't delivering things that could be more effective," he told the BBC.
Senior US economist Michael Hanson from Bank of America said although he had not been expecting any firm announcements on further QE, he had been surprised by the strength of Mr Bernanke's comments on the government's need to act.
"He was very explicit, more so than we were anticipating, that Congress and the administration needs to do more in fiscal policy to help the recovery along," Mr Hanson told BBC News.
'Disappointing' recovery The Federal Reserve had already said that it plans to keep US interest rates at the current low level of between zero and 0.25% until the middle of 2013.
Last Updated at 26 Aug 2011, 18:47 GMT *Chart shows local time 
And analysts suggested they might consider more minor measures short of quantitative easing over the next couple of months to try to support financial markets and hold off doing any more for the moment.
"They are not completely out of tools, but they are not comfortable at this point adopting a much more aggressive approach like QE3," said Bank of America's Mr Hanson.
"But if it turns out that we continue to get a setback on growth and unemployment continues to rise... then QE3 becomes a much more likely possibility."
Earlier in the week, world stock markets had risen as investors speculated that the central bank may pave the way for a third round of quantitative easing.
But they have been in retreat since Thursday when opinion moved towards the speech not revealing plans for any new measures.
US markets dipped further immediately after the speech but later recovered, with the Dow Jones up 1.4% in afternoon trading.
BBC business reporter Caroline Hepker, speaking from the trading floor at the New York Stock Exchange, described how shares had seen an "upswing" after an initial sell-off.
"But they are very light trading volumes here as a lot of people on the East Coast are preparing for the hurricane that we are expecting over the weekend," she cautioned.
The earlier data from the Commerce Department reiterated the low rate of growth the US is experiencing, as consumer spending remains weak in the face of high unemployment and higher energy bills.
Mr Bernanke admitted that the pace of the recovery in the US had "proved disappointing thus far".
But he added that he expected growth in the second half of the year to pick up as "temporary factors", including the increase in commodity prices and the Japanese earthquake and tsunami, begin to have less of an impact.
The announcement was made at Apple's headquarters in California. Apple has unveiled the latest iteration in its iPhone range, but there was no sign of the widely rumoured iPhone 5. The iPhone 4S, as the new model will be known, boasts an improved camera and significantly extended battery life.
