China's fixed-asset investment (FAI) eased in the first half of this year as the economy continues to firm up, data released Monday showed.

FAI grew 8.6 percent year on year in the first six months, down 0.6 percentage points from the first quarter, according to the National Bureau of Statistics (NBS).

Total investment from January to June stood at 28.06 trillion yuan (4.15 trillion U.S. dollars), according to a statement of the NBS.

Primary industry posted the fastest FAI growth, up 16.5 percent year on year, followed by the service industry with an increase of 11.3 percent and 4 percent in the secondary industry.

Investment in the manufacturing sector rose 5.5 percent in the first half, up 0.4 percentage points from the first five months.

Private sector investment grew 7.2 percent in the first six months to 17.02 trillion yuan, accounting for 60.7 percent of the total, according to the statement.

The bureau's calculation does not include FAI by farmers. It includes projects with planned investment of more than 5 million yuan, as well as all property development.