* Non-financial ODI in Jan-Aug drops 41.8 pct to $68.72 bln
* Jan-Aug FDI slips 0.2 pct y/y to 547.94 bln yuan
* 'Irrational' overseas investment effectively curbed - ministry (Adds details)
BEIJING, Sept 14 (Reuters) - China's outbound non-financial investment (ODI) slumped 41.8 percent in January-August from a year earlier, as authorities kept a tight grip on outflows for what they call "irrational" overseas projects.
The grip is part of efforts to curb speculative capital outflows that had pressured the yuan currency.
For August, ODI declined 24.8 percent from a year earlier to $11.52 billion, Reuters calculated from official data. The Ministry of Commerce, which on Thursday released data on the first eight months of the year, did not give a figure for August alone.
"Irrational" overseas investment has been effectively curbed, the ministry said. China's state council said in August that China will limit overseas investment in property, hotels, entertainment, sports clubs and film industries.
Dalian Wanda Group said last month that it had scrapped plans to buy Nine Elms Square in London, the latest setback for the Chinese conglomerate, and one connected with Beijing's tight controls on overseas investment.
At least two of HNA Group's overseas deals have hit a hurdle as the Chinese conglomerate struggles to take money out of China amid a crackdown by Beijing on capital outflows to fund acquisitions it sees as risky, according to four people familiar with the process.
For January-July, ODI had fallen 44.3 percent from a year earlier to $57.2 billion.
ODI that went into 52 countries involved in China's "Belt and Road" initiative totalled $8.55 billion in the January-August period, accounting for 12.4 percent of the total, the ministry said.
Capital outflows have eased in recent months in the face of tighter regulations and the dollar's retreat. The yuan has surged in recent months, including a 2.1 percent gain in August, its best month since 1994.
In January-August, foreign direct investment (FDI) into China fell 0.2 percent from a year earlier to 547.94 billion yuan ($83.72 billion), the ministry added.
FDI in China's high-tech manufacturing sector rose 15 percent in the first eight months from a year earlier, while investment in high-tech services sector grew 21.4 percent, the ministry said.
For August alone, FDI rose 9.1 percent to 62.52 billion yuan. The ministry reported a 1.2 percent decline for January-July.
China has pledged to further open up its economy to foreign investors, including allowing investment into previously restricted industries.
The commerce ministry said in August that China has clear advantages in attracting FDI over the medium and long-term. ($1 = 6.5451 Chinese yuan) (Reporting by Elias Glenn and Stella Qiu; Editing by Richard Borsuk)