* HSI +0.8 pct, H-shares +0.4 pct, CSI300 -0.5 pct
* PetroChina up, banking and real estate slip
* Hong Kong property jumps, Cheung Kong at 7-year high (Updates to midday)
HONG KONG, July 30 (Reuters) - Hong Kong's benchmark index climbed on Wednesday, heading for a seventh day of gains on the back of a bullish property sector, while China stocks took a breather after recent strength.
China's major indexes broke a long-running streak as early gains led by index heavyweight PetroChina Co Ltd were offset by plunging real estate and banking shares.
By midday, the Shanghai Composite Index was down 0.1 percent at 2,180.39 points, breaking a six-day winning streak, the longest since August 2013.
The CSI300 of the leading Shanghai and Shenzhen A-share listings fell 0.5 percent.
PetroChina was among top index boosts in Shanghai, climbing more than 6 percent at one point. The government said on Tuesday it had launched a corruption investigation into former domestic security chief Zhou Yongkang, who served as CNPC's general manager from 1996-1998.
PetroChina shares had previously slid on rumours that Zhou would be investigated; traders said the rally may have been due to relief as the uncertainty had been cleared away.
The slide in real estate shares was due to profit-taking, analysts said, led by a sell-off in shares of property developer Vanke. It shed nearly 2 percent on Wednesday after having risen nearly 20 percent since mid-July on reports that local governments were easing up on property purchase curbs.
"The market has reflected the loosening of real estate policies in the past months," said Xiao Shijun, an analyst at Guodu Securities in Beijing. "It's time for the market to conduct an adjustment."
The Shanghai index will likely float between 2,350 and 2,400 in the short term, benefiting from recent policies, he said.
In Hong Kong, the Hang Seng Index rose 0.75 percent to 24,825.69 points, near its November 2010 high. The China Enterprises Index of the top Chinese listings in Hong Kong gained 0.38 percent.
Sentiment was underpinned by the property sector, which gained on an improved outlook and ahead of earnings.
"Hong Kong property outshone and remained strong as the outlook has improved while an upward revaluation of (local) property by some brokerages fuelled buying," said Alex Wong, a director at Ample Finance Group in Hong Kong.
Cheung Kong Holdings, whose first-half results are expected on Thursday, gained 2.04 percent to its highest since October 2007. New World Development surged 3.6 percent, Sino Land rose 2.5 percent and Sun Hung Kai Properties was up 2.7 percent. (Reporting by Donny Kwok; Additional reporting by Shanghai Newsroom; Editing by Jacqueline Wong)