SHANGHAI, China — China's economy expanded by a stunning 9.9 percent in 2005 according to data released yesterday that suggests it may now rank fourth-biggest in the world.

Spurred by strong export growth and foreign investment, growth in the fourth quarter was also up 9.9 percent from the same period a year ago.

For all of 2005, China's gross domestic product totaled 18.23 trillion yuan ($2.26 trillion), the National Bureau of Statistics said in a statement.

According to recent estimates, that would place it fourth in the world, behind the United States, Japan and Germany, after steamrolling past Britain, France and Italy.

The economy is showing hardly any signs of slowing down despite efforts by the communist leadership to curb excessive investments in construction and redundant factories that have strained transport networks and supplies of energy and other resources.

Growth in 2004 was 10.1 percent — a figure recently revised upward from the original 9.5 percent, based on an economic census that uncovered much larger than expected growth in the services sector.

Chinese economic data are notoriously unreliable, and some economists questioned if the figures announced yesterday were understating real growth, given a nearly 30 percent surge in exports and strong domestic spending.

The 9.9 percent figure "doesn't quite capture it," said Stephen Green, senior economist for Standard Chartered Bank in Shanghai. "One could say that 9.9 percent is a very convenient number; it's not 10 percent. Ten percent might scare people, and might create more trade friction with the U.S."

While many other countries have yet to release 2005 GDP figures, according to the most recent figures available and projections for 2005 growth, China's economy is now bigger than those of Britain, France and Italy.

While its growth has been meteoric, China remains a developing economy: That wealth is spread among a population of 1.3 billion people, a large share of whom live in poverty.

The Statistics Bureau said GDP growth in the first three quarters of 2005 was revised upward from preliminary estimates, to 9.9 percent in the first quarter, 10.1 percent in the second and 9.8 percent in the third, from 9.4 percent, 9.5 percent and 9.4 percent, respectively.

Earlier this month, state media carried reports citing government officials saying 2005 GDP growth was estimated at 9.8 percent.

The economy has consistently overshot official targets for the past several years. Perhaps partly for that reason, officials presenting the report did not offer forecasts for 2006. Government economists earlier offered predictions of between 8.5 percent and 9 percent for this year.

One of the key factors behind last year's better-than-expected performance was strong investment in construction and factories. Such spending grew a robust 25.7 percent to 8.9 trillion yuan ($1.1 trillion), and officials warned of problems in keeping it under control.