* Hang Seng closes near days low, down 0.5 pct
* Shanghai Composite down 0.5 pct, B-shares slide 5.3 pct
* China property stocks weak on tightening fears (Updates to close)
By Vikram Subhedar and Yixin Chen
HONG KONG, April 27(Reuters) - Hong Kong and China shares reversed earlier gains to close lower on Wednesday after a sharp slide on the speculative Shanghai B-share index, as concerns about additional policy tightening by Beijing pulled the markets further away from their recent highs.
China's main stock index fell for the fourth day in a row in thin volume, as property stocks dropped on reports the government could unveil new tightening measures for the sector soon.
The Hang Seng Index fell 0.5 percent to 23,892.8 in another day of light trading.
Traders have been hoping Hong Kong could rally past the index's 2011 high of 24,468.6, hit earlier this month, but the speed with which the market reversed gears following Wednesday's Shanghai B-index slippage showed there is not solid ground for gains at present.
The Shanghai B-share index of dollar-denominated stocks, which is largely illiquid, fell 5.3 percent for the day with twice its recent average volume. Investors dumped shares on talk that the rumored launch of an "international board" of shares of foreign companies could detract from interest in the B-share market.
Authorities have long planned the international board in Shanghai, and one media report this week suggested preparation for the launch could be moving forward. [ID:nL3E7FQ07O]
"There are rumors that the international board will come out over the May Day holiday, though I think the likelihood of that is not great," said Cheng Yi, analyst at Xiangcai Securities in Shanghai.
Cheng and some traders also cited dollar weakness and concerns about the future of the U.S. currency ahead of the end of a two-day U.S. Federal Reserve policy meeting as another reason for investors dumping B-shares.
Caution about the Fed decision as well as rumours Chinese authorities could make some sort of announcement on monetary tightening or other measures during the coming three-day weekend kept turnover in Hong Kong and China light.
Turnover on the main board in Shanghai inched higher to 114 billion yuan ($17.5 billion), versus 112 billion yuan on Tuesday, hovering around a 10-week low.
PROPERTY SHARES WEAK, BANK RESULTS EYED
The sub-index of property companies in Shanghai dropped 1.3 percent after reports that the government would announce further steps to curb prices. The property index in Hong Kong fell 0.5 percent.
Vanke , the largest developer by sales, fell 1.8 percent, while Zhongtian Urban Development Group tumbled by its 10 percent daily limit.
In Hong Kong, China Resources Land fell 2.1 percent.
Investors also shunned companies that had posted disappointing first-quarter results with China Life down 1.7 percent and China Unicom sliding 2.5 percent.
Chinese banks, often considered a proxy for the economy, are set to report first quarter earnings in coming days and could help support the broader market.
The sector is larrgely expected to report robust profits despite more than a year of government efforts to tighten capital and fight inflation in the world's second-largest economy. [ID:nL3E7FO09Q]
Analysts expect mostly double-digit profit growth for the quarter, as the banks increased their loan portfolios and the margins on those loans in the face of moves to take cash out of the system through increased required deposits with the central bank.
May Yan, Asia ex-Japan banks analyst at Barclays Capital, said in a note that net interest margins, a key performance criteria for banks, were likely to expand quarter-on-quarter and drive strong results.
Larger banks such as Agricultural Bank of China Ltd , scheduled to report its results after the market closes, which have low funding costs, were likely to see greater benefits, said Yan.
(Editing by Richard Borsuk)