China's economic growth will decelerate to around 8.1 percent this year and edge up to 8.7 percent in 2013, Stephen Green, economist with Standard Chartered Bank (China), said Saturday.

He said in an interview with Xinhua that China's manufacturing activity is far from optimistic despite the country's Purchasing Managers Index (PMI) for the manufacturing sector rose slightly in January.

The China Federation of Logistics and Purchasing said Wednesday in a statement on its website that China's PMI rose to 50.5 percent in January, the highest level since October. The PMI stood at 50.3 percent in December, and 49 percent in November.

The manufacturing sector is currently going through contraction, Green said.

He sees China's gross domestic product (GDP) growth will be the slowest in the first quarter and gradually pick up later on, bringing the growth rate for 2012 to around 8.1 percent.

China's economy expanded by 9.2 percent in 2011 from a year earlier and 8.9 percent year-on-year in the fourth quarter, according to the National Bureau of Statistics (NBS). The quarterly growth was the slowest in 10 quarters.