As Barack Obama undertakes his first official visit to China, the fate of the renminbi is again in the spotlight of the international currency market.

Ever since the People's Bank of China changed the wording of a key currency policy statement last week, there has been speculation about whether and when the Chinese currency will be allowed to strengthen.

The wording change was significant because the Chinese authorities, which tightly manage the value of the renminbi, have kept the currency stable since the summer of last year. And the impact was immediate: in the past few days, forecasts for the appreciation of the renminbi against the dollar have risen to their highest level in a year, predicting a 3.4 per cent rise over the next 12 months.