* Shanghai Composite up 3.3 percent after week-long holiday
* HK shares just below two-year peak, local property leads
* Rally on strong volume indicates strong investor confidence
* Hang Seng Index RSI at 80, highest since pre-crisis peak (Updates to midday)
By Vikram S.Subhedar and Farah Master
HONG KONG/SHANGHAI, Oct 8 (Reuters) - China's key stock index climbed 3.3 percent on Friday morning after the week-long National Day holiday, catching up with firmer global markets and as stronger commodities prices bolstered metals and mining issues.
The Shanghai Composite Index <.SSEC> was up 3.3 percent by the midday break at 2,742.8 in heavy volume as the benchmark vaulted past the 2,700 level that had acted as overhead resistance for nearly two months. The jump also lifted Hong Kong's stock market, with the benchmark Hang Seng Index <.HSI> up 0.75 percent
The Shanghai Composite also broke through its 125-day moving average -- referred to as the "half-year" moving average, a closely watched indicator.
Shanghai's stock market, one of the world's worst performers, is still down about 16 percent so far this year, with China's clampdown on bank lending and the property market having taken a toll despite robust economic growth.
"Gains in overseas markets during the holiday and stronger prices for key commodities, such as oil and gold are key factors boosting the Shanghai market today," said Wen Lijun, analyst at Nanjing Securities.
Commodities plays were among the biggest gainers, with Yanzhou Coal Mining Co Ltd <600188.SS>, Zijin Mining Group Co Ltd <601899.SS> and Jiangxi Copper Co Ltd <600362.S> all reaching their 10 percent trading limits.
Property counters shrugged off news that Shanghai's government had issued rules to limit home buyers to one new apartment. [ID:nTOE696096]
Shanghai's property sub-index <.SSEP> was up 1.9 percent, with large property developers Gemdale Corp <600383.SS> up 3 percent and Poly Real Estate Group Co Ltd <600048.SS> 3.7 percent higher.
Property stocks have slumped since mid-August after the government announced measures to cool speculation in the country's red hot property market.
"The door for the market to rise has been opened, but a clear turn around needs time. Low valuations of large caps are likely to give short-term momentum," said Chen Shaodan, analyst at China Development Bank Securities in Beijing.
Volume nearly doubled to 96 billion yuan ($14.35 billion) from 51 billion yuan last Thursday, while gaining shares thrashed losers 874 to 39.
HK FIRM, PROPERTY PLAYS RISE
A strong mainland market spurred gains in Hong Kong as local property plays resumed their stellar run since September after a brief consolidation earlier this week.
The benchmark Hang Seng Index <.HSI> was up 0.75 percent at 23,056.69 at the midday trading break, just 0.2 percent below its November 2009 peak and a two-year high.
Investors piled into Hong Kong developers on expectations that easier U.S. monetary policy will keep money cheap and boost prices of local assets.
Analysts have reined in fears the government will announce overly negative policies in its policy address next week and focus instead on increasing land supply and, on a smaller scale, support affordable housing schemes.
Analysts at Bank of America Merrill Lynch said they expected the local property market to anticipate rising rates towards the end of 2011, on top of the prospect of more supply over the following two years.
"A liquidity bubble aided by undersupply may eventually burst, but the party looks set to continue for a while," said the analysts in a note to clients.
Cheung Kong (Holdings) Ltd <0001.HK> rose 4.2 percent to a 28-month high and provided the biggest boost to the broader market. Its shares are up nearly 25 percent since end-August.
Sun Hung Kai Properties Ltd <0016.HK> rose 2.8 percent.
Energy counters underperformed the broader market as oil prices eased. CNOOC Ltd <0883.HK> fell a percent and was the biggest drag on the Hang Seng Index.
The Hang Seng Index's 12 percent rally from the start of September on the back of a strong recovery in turnover has taken it well into overbought territory according to its relative strength index (RSI), now at 80. The last time the RSI was at this level, the HSI was trading near record highs back in September 2007. ($1=6.690 Yuan) (Editing by Chris Lewis)