President Barack Obama yesterday urged China to strengthen its currency as tensions over exchange rates and trade broke through a carefully orchestrated show of co-operation between Washington and Beijing.

Mr Obama made his comments after a three-hour meeting in Beijing with President Hu Jintao, during which both leaders pledged to work together on pressing international issues.

However, the US president also joined in the growing chorus of international voices calling on China to allow the renminbi to appreciate.

“I was pleased to note the Chinese commitment made in past statements to move toward a more market-oriented exchange rate over time,” he said at a joint appearance with Mr Hu. Such a move would “make an essential contribution to the global rebalancing effort”.

The reference to “past” statements could imply that China did not make any new commitments yesterday. Mr Hu did not mention the currency issue in his statement, although he did call on both governments to refrain from protectionism, a criticism of recent US measures on Chinese steel pipes and tyres.

Coming at a moment when Chinese prestige is growing and the US is facing enormous difficulties, Mr Obama's trip has symbolised the advent of a more multi-polar world where US leadership has to co-exist with several rising powers, most notably China.

The two leaders both made prepared statements, adding to the impression that Mr Obama's visit has been one of the most tightly scripted in recent years.

In their comments and a joint statement, the pair spelt out a programme for ever-growing co-operation, including stronger military ties, research initiatives on climate change and clean energy and “a dialogue on human space flight”.

On Iran, where the US has been pushing China to take a harder line against Tehran, Mr Obama used stronger language: “Iran has an opportunity to present and demonstrate its peaceful [nuclear] intentions but if it fails to take this opportunity, there will be consequences.” Mr Hu said it was important to resolve the issue through negotiations.

China's currency has been effectively re-pegged to the US dollar since mid-2008. In recent weeks a number of international officials and governments have complained about the advantage this gives Chinese exporters.

Yu Yongding, a leading Chinese economist and former central bank adviser, said Europe and China “should play together and put pressure on the US to change its monetary policy”. China and much of the world was being held “hostage” by US policy, he said.