As China's economy increase slows, the United States' demand growth for oil outstripped China's last year for the first time since 1999, according to the Paris-based International Energy Agency.

According to an IEA report, US oil demand rose by 390,000 barrels a day in 2013, or 2 percent, while Chinese demand increased by 295,000 b/d, the weakest in at least six years. Oil demand directly indicates economic growth as petroleum and diesel are major fuels for industry.

In the past 10 years, China's oil demand has grown rapidly, driven by its high economic growth, while US oil demand has been declining since 2005. Analyst said it is a sign the US economy is rebounding when its oil demand growth surpassed China's.

According to an earlier report from the IEA last year, China is expected to overtake the US to become the world's largest oil importer in the 2020s as emerging economies, rather than developed ones, will claim most of the world's energy supplies.

China will be the main contributor to the increase in global energy use before 2020, and then will be replaced by India as the world's biggest driving force for energy demand, the report said.

The CNPC Economics and Technology Research Institute said last week that China's oil use growth decelerated in 2013. Crude oil consumption was up 2.8 percent last year to 487 million metric tons. Its growth rate was 1.7 percentage points lower than in 2012.

Imported oil accounted for 58.1 percent of the country's oil supply, the institute said.

During the first decade of this century, China's oil consumption rose consistently, with average annual growth of 6.7 percent. That trend ended in 2011.