* CSI300 -0.7 pct; SSEC -0.6 pct; HSI +0.3 pct
* Airlines up after China says further yuan depreciation unlikely
SHANGHAI, Aug 13 (Reuters) - China stocks gave up early gains and ended Thursday morning lower in thin trading, pointing to investor caution and an uncertain economic outlook after the yuan's devaluation.
Airline operators, which tumbled over the past two days, rebounded, after China's central bank said there is no basis for further depreciation in the yuan, soothing fears that a persistently weaker currency would hurt carriers' profit.
But most other sectors fell. The CSI300 index lost 0.7 percent, to 3,989.12 points at the end of the morning session, while the Shanghai Composite Index fell 0.6 percent, to 3,862.06 points.
Gerry Alfonso, a director at Shenwan Hongyuan Securities, said investors are "apparently taking a wait-and-see attitude" and "behaving rather cautiously."
Defence businesses, which had been rising sharply recently on expectations of consolidations, fell over 4 percent on profit-taking, while the agricultural sector also posted a big correction.
Stocks rose in Hong Kong, though. The Hang Seng index added 0.3 percent to 23,986.76 points, while the Hong Kong China Enterprises Index gained 0.4 percent, to 11,089.81.
Li Ning Co Ltd rose over 4 percent, after the Chinese sportswear maker posted a narrower first-half loss as it resumed opening new sales outlets in lower-tier cities after years of restructuring, and said it aims to return to profit by the end of 2015.
China Zhongwang Holdings, the world's second-biggest aluminium products maker, failed to convince investors in a detailed statement on Thursday denying allegations made by a short seller that accused the company of doctoring its books.
Its stock opened 18 percent lower and was still down nearly 10 percent by midday.
Hong Kong Exchanges & Clearing Ltd (HKEx) shares fell, despite a doubling in net profit during the April-June period, as its chief executive warned that market turmoil in China could turn investors off mainland shares and delay a link with Shenzhen. (Reporting by Samuel Shen and Pete Sweeney; Editing by Eric Meijer)