* CSI300 +1.1 pct; SSEC 1 pct; HSI -0.5 pct
* Tencent slumps after CEO Pony Ma reduces holdings
* "Modern Silk Road" concept back in the spot light
By Samuel Shen and Pete Sweeney
SHANGHAI, April 14 (Reuters) - Hong Kong stocks retreated on Tuesday morning after eight straight sessions of gains, as Tencent Holdings Ltd slumped after chief executive Pony Ma reduced his holdings in China's biggest social networking and online entertainment firm.
But Chinese shares continued to rise, hitting another seven-year high, with a surge in infrastructure-related stocks offsetting losses in financial shares as the "Modern Silk Road" concept comes back into the spot light.
The recent surge in Hong Kong stocks helped push Tencent's market capitalisation over $200 billion for the first time on Monday, making it more valuable than U.S. tech firms such as Amazon.com Inc, IBM Corp and Oracle Corp .
But on Tuesday morning, the stock tumbled about 5 percent, heading towards its biggest daily fall in nearly a year, after exchange disclosures showed Ma last week sold 20 million shares for HK$3.22 billion.
Although the news triggered profit-taking, many investors believe Hong Kong's bull run is not yet over.
"We expect the flows to invest in Hong Kong from mainland investors to continue," said Mandy Chan, head of Chinese and Hong Kong equities, HSBC Global Asset Management.
Chan said that many Hong Kong stocks, especially small caps, are still cheaper than mainland-listed shares, "so it was only a matter of time before we see a pick-up in these stocks."
The Hang Seng index dropped 0.5 percent to 27,880.90 points by the midday break, while the Hong Kong China Enterprises Index lost 0.3 percent to 14,545.85.
But China stocks continued to power ahead, with the CSI300 index rising 1.1 percent and the Shanghai Composite Index gaining 1.0 percent.
Shenzhen's Nasdaq-style start-up board ChiNext keeps smashing records, rising 0.6 percent, despite warnings that the board's valuation already exceeds the level seen at the peak of the U.S. dot-com bubble.
The "Silk Road" concept was again the darling of investors on Tuesday, with the CSI300 Infrastructure Index and the CSI Machinery Index jumping more than 4 percent.
China Central Television, the country's predominant state television, begins a TV series on Tuesday promoting China's ambitious "One Road, One Belt" project.
Under the project, China plans to stoke foreign demand for its industrial output by financing infrastructure investment around Asia, aiming to build the 21st century Maritime Silk Road and a land-based counterpart. Analysts say the drive will benefit Chinese train makers, port operators and electricity producers. (Editing by Jacqueline Wong)