* CSI300 -1.0 pct; SSEC -1.5 pct; HSI -0.1 pct
* Yuan falls against the dollar, traders see downward pressure
* Sentiment weak with no positive catalyst seen - analyst
HONG KONG, Aug 18 (Reuters) - Shares in China and Hong Kong fell on Tuesday as the yuan eased against the dollar, reigniting fears that Beijing may be intent on a deeper devaluation of the currency despite the central bank's comments that it sees no reason for a further slide.
The CSI300 index fell 1 percent to 4,038.26 points by the end of the morning session, while the Shanghai Composite Index lost 1.5 percent to 3,935.33 points.
"Anticipation of further devaluation discouraged investors from holding yuan-denominated assets," said Alex Wong, a director at Ample Finance Group in Hong Kong.
"We see no positive catalyst that can boost the market in the medium run. Investors are not keen to enter the market when they see very limited upside potential," Wong added.
China CSI300 stock index futures for August fell 0.6 percent, to 3,964, 74.26 points below the current value of the underlying index.
The yuan fell against the dollar on Tuesday despite a slightly stronger midpoint set by the central bank, and traders expect the currency to remain under downward pressure as the economy struggles.
The People's Bank of China devalued the currency last week by nearly 2 percent, triggering an avalanche of selling by investors who feared Beijing wanted to engineer a much sharper decline to support weak exports. The PBOC was later forced to step into the market and tell state banks to support the currency.
Shares of importers and firms with high U.S. dollar-denominated debt have been under pressure along with Chinese airlines who face higher fuel bills following the devaluation.
Among airlines, China Eastern fell 3.9 percent and China Southern tumbled percent.
Property shares also slid on Tuesday despite encouraging home price data, with the SSEC property sub-index down 3 percent.
Chinese home prices rose in July for a third consecutive month, fuelled by improved sales and market sentiment, suggesting the property market is slowly recovering in a rare counterpoint to a growing list of grim economic indicators.
China Vanke, the country's largest property developer, said on Monday that the housing market is slowly emerging from a year-long slump, but it will take time to see a full recovery.
Losses in Hong Kong were milder, with the Hang Seng index off 0.1 percent at 23,795.11 and the Hong Kong China Enterprises Index edging down 0.2 percent to 10,944.25.
Insurers remained under pressure, with Ping An Insurance falling 1.2 percent.
Credit Suisse analysts, citing initial estimates from local media, said that the two explosions in the Chinese port of Tianjin last week that killed more than 100 people could generate total insurance losses of $1 billion to 1.5 billion.
The index measuring price differences between dual-listed companies in Shanghai and Hong Kong stood at 136.85.
A value above 100 indicates Shanghai shares are pricing at a premium to shares in the same company trading in Hong Kong, and vice versa.
Under the Hong Kong-Shanghai Stock Connect scheme , a net 0.19 billion yuan went northbound to Shanghai, a tiny fraction of the 13 billion yuan daily quota.
The total volume of A shares traded in Shanghai was 28.07 billion shares, while Shenzhen volume was 20.75 billion shares.
The total trading volume of companies included in the HSI index was 0.5 billion shares.
China stock market graphics suite reut.rs/1HcUe19
(includes timeline of crash, PE ratios, market caps)
A-share account openings spike bit.ly/1wvJ9S9
Comparison of stock indexes and selected company stocks
Chinese A-shares vs developed and emerging stocks
Reporting by Donny Kwok; Editing by Kim Coghill