US Federal Reserve chairman Ben Bernanke has criticised countries like China that run large trade surpluses.
"Currency undervaluation by surplus countries is inhibiting needed international adjustment," he said in a speech to the European Central Bank
He said that by buying dollars, these countries were hurting the US recovery and the global economy with it.
He also defended the Fed's policy of "quantitative easing", which has been criticised by China and Germany
Defending QE
China, Germany and others have attacked the Federal Reserve in recent weeks for its decision to purchase another $600bn of US government debt in a bid to stimulate the US economy.
They say that the policy will unfairly devalue the dollar in currency markets, and that this could lead to inflation and asset bubbles elsewhere in the world.
The Chinese also argued the Fed had failed to take account of its responsibility for protecting the value of the dollar as a global reserve currency.
In his speech, Mr Bernanke defended the policy as the right response to falling inflation and high unemployment in the US.
He also said it was a natural extension of monetary policy, given that interest rates were near zero and could not be cut further.
On the attack
But Mr Bernanke went further than this, hitting back against his critics.
US DOLLAR V CHINESE RENMINBI
He said that their policy of accumulating dollar reserves in order to weaken their currencies and help maintain a trade surplus would hurt the recovery in industrial economies, and this in turn could harm the entire global economy.
"For large, systemically important countries with persistent current account surpluses, the pursuit of export-led growth cannot ultimately succeed if the implications of that strategy for global growth and stability are not taken into account," he said.
He spoke of a two-speed recovery, in which developing economies like China and India had rapidly bounced back, while industrialised countries like the US, Europe and Japan were growing much more slowly and suffered from high unemployment.
"Because a strong expansion in the emerging market economies will ultimately depend on a recovery in the more advanced economies, this pattern of two-speed growth might very well be resolved in favour of slow growth," he said.