The amount of yuan held by foreign banks has risen significantly, in anticipation of another rise in the value of China's currency.
Chinese firms are buying up foreign debt
The Chinese government revalued its currency in July, allowing it to trade at a higher rate against the US dollar.
Speculators expect the yuan to rise further as China comes under pressure to ease trade tensions with the US.
China's trade surplus may hit $100bn (£56bn) this year, exacerbating its dispute with the US over cheap exports.
Many US politicians say China's currency is artificially undervalued, giving it an advantage in the export market and threatening US jobs.
In the past three months, yuan-denominated debt held overseas rose 3.8% to $266bn, according to figures released by the government.
Levels of short-term debt - regarded by economists as a barometer of the likely speculation in a currency - rose 7.9% to $141.3bn.
Any further appreciation in the value of the yuan would increase the worth of yuan-denominated assets, making them attractive for foreign investors to hold.
Beijing has tried to make it more difficult for foreign companies to buy bonds and other financial instruments paid in yuan.
However, this has had little effect because of a widespread belief that it will have to further loosen the rate at which the yuan trades against the dollar and other currencies.
"The rise in China's short-term foreign debt reflected continued hot money inflows, showing speculation on a further rise in the yuan remains strong, despite the revaluation," Xiao Minjie, an economist at the Daiwa Institute of Research, told Reuters.
US Treasury Secretary John Snow is expected to make the case for a further relaxation in the yuan's exchange rate when he visits China later this month.
He will hold talks with Chinese officials later this month amid growing evidence that the yuan's revaluation has not slowed down its surging rate of exports.
China's trade surplus rose threefold in the first eight months of 2005 to $60bn, more than for the whole of 2004.
John Snow is expected to press the case for further currency reform
The Chinese government says it expects the full year surplus to reach between $90bn and $100bn.
It has been fuelled by a huge expansion in textile exports to the US and Europe after the abolition of quotas at the start of the year.
A further round of talks aimed at creating a framework for Chinese textile exports to the US are to take place in Beijing later this month.
Previous discussions have failed to resolve an impasse over the level of Chinese clothing imports to the US.
China's trade surplus with the US hit a record $162bn last year.