China is making progress in a five-year effort launched in 2006 to improve energy efficiency in its fuel-guzzling economy, a state news agency said Tuesday, but the country is still falling short of its annual targets.

Energy consumption per unit of economic output fell by 3.66 percent last year, after a 1.79 percent drop in 2006, the Xinhua News Agency said, citing the National Development and Reform Commission, the country's top planning agency.

But that was short of the minimum 4 percent annual decline required by the plan, which calls for a 20 percent overall improvement by 2010.

Beijing imposed the efficiency goals as part of efforts to clean up China's heavily polluted environment and reduce growing reliance on imported oil, which communist leaders see as a security threat.

Chinese industries use 20 to 100 percent more energy per unit of output than their U.S., Japanese and other counterparts, according to the World Bank. China's government says the gap is even bigger, putting energy use at 3.4 times the world average.

China is the world's second-biggest oil consumer and importer after the United States and also relies heavily on domestic coal supplies to fuel an economy that is expected to grow by at least 9 percent this year.

The region with the biggest improvement last year was Beijing, where energy use per unit of economic output shrank by 6 percent, Xinhua said. It said that was due in part to special efforts to clean up the city for the Summer Olympics this August.

The government has closed a string of smaller, less efficient coal-fired power plants since 2005.

So far, plants with a total generating capacity of 26 million kilowatts have been shut down, Xinhua said. It said that would save 32.6 million tons of coal and reduce carbon dioxide emissions by more than 550,000 tons per year.