BEIJING, July 16 (Xinhua) -- China's property investment posted slower growth in the first half of this year, partly due to strengthened regulation on real estate markets, the statistics authority said Monday.

Investment in property development increased 9.7 percent year on year in the first six months, slightly slower than the 10.2-percent expansion recorded in the January-May period, the National Bureau of Statistics (NBS) said in a statement.

The growth pace marked the slowdown for a third straight month from the peak of the 10.4-percent rise in the first quarter.

NBS data showed investment in the real estate sector amounted to 5.55 trillion yuan (around 830 billion U.S. dollars), with 70.2 percent of the total pumped into residential projects, which also slowed down mildly.

The government has continued its tough stance on property sector regulation this year, curbing home market speculation and cleaning up the illegal financing channels of property developers.

Seen as a major prop to the Chinese economy, the once-overheated sector has thus far remained largely stable amid efforts to help defuse financial risks.

In breakdown, developers built about 7.1 billion square meters of housing in the January-June period, up 2.5 percent year on year, of which more than two-thirds were residential buildings.

Commercial housing sales measured by floor area rose 3.3 percent year on year, up 0.4 percentage points compared with the first five months. At the end of June, housing inventories stood at about 551 million square meters, down by 9.27 million square meters from a month earlier.