* HSI +0.3 pct, H-shares +0.3 pct, CSI300 -0.1 pct
* Hong Kong and mainland property stocks gain
* Sinopec, PetroChina shares up on industry consolidation
By Natalie Thomas and Grace Li
BEIJING, May 13 (Reuters) - Hong Kong shares extended gains on Tuesday, led by gains in technology and property stocks amid speculation the government may relax the city's stamp duty rules.
China shares were down slightly, as investors locked in some of Monday's strong gains following the news of deepening capital reforms, though property continued to perform strongly.
By midday, the Hang Seng Index was up 0.3 percent at 22,324.14 points. The China Enterprises Index of the top Chinese listings in Hong Kong gained 0.3 percent.
The CSI300 index of the largest Shanghai and Shenzhen A-share listings was down 0.1 percent, while the Shanghai Composite Index was down 0.1 percent at 2,051.63 points.
Leading the gains in Hong Kong were technology firms, with Lenovo Group Ltd up 3.2 percent, and Tencent Holdings Ltd up another 1.8 percent following Monday's increase of more than 5 percent.
Hong Kong property stocks also registered some of the strongest gains on the hope that the government may lengthen the time before homeowners have to pay double stamp duty if they fail to sell their second home.
Among the top performers were China Overseas Land & Investment Ltd which soared 3.6 percent, while Sino Land Co Ltd gained 2.7 percent.
But analysts remained cautious, believing the sector may be over-reacting to the news.
"Even if property stocks continue to rebound today, it seems the momentum is not very strong," said Castor Pang, head of research at Core Pacific-Yamaichi in Hong Kong.
Analysts were similarly sceptical about the mainland's property performance, even as the CSI property subindex gained a further 1.4 percent after breaking its eight-day losing streak on Monday.
"As a whole the real estate market is not improving at the moment, so these current rebounds basically just indicate expectations and hopes for government intervention," said Du Changchun, an analyst at Northeastern Securities in Shanghai.
Elsewhere, shares in Chinese state energy giant PetroChina Co Ltd jumped 1.1 percent on the mainland and 1.6 percent in Hong Kong after the firm said it would sell more pipeline projects as part of efforts to streamline the company and cut back on capital investment.
The move, which is part of a wider plan to increase private involvement in the sector, also lifted China Petroleum and Chemical Corp (Sinopec) shares by 0.8 percent on the mainland and 0.6 percent in Hong Kong.
In Hong Kong, shares in Macau casino operator SJM Holdings Ltd, fell 3.6 percent in the morning session after announcing lacklustre first quarter earnings that missed expectations as the company faces increasing competition in the world's largest gambling hub.
Additional reporting by Chen Yixin; Editing by Jacqueline Wong