China said on Monday that its population -- already the world's largest -- increased by 6.3 million last year to hit 1.341 billion by the end of 2010.
The rise was roughly equal to the population of the city of Rio de Janeiro.
The 2010 figure was released by the National Bureau of Statistics, which called it a preliminary estimate.
A final figure will be published in April when the government finishes tabulating data obtained in a census conducted late last year, the nation's first full census in a decade.
China's population was calculated at 1.295 billion in the last full census in 2000.
China has previously said its so-called "one-child" policy -- which generally limits people to one offspring, with exceptions for certain groups -- has averted 400 million births since its imposition in 1980.
The nation had a population of 594 million, less than half the current figure, in its first census in 1953.
Explore further: Understanding the economics of human trafficking