* SSEC 0.5 pct, CSI300 0.6 pct, HSI 0.7 pct
* Energy sector boosted after oil price jumped over 10 percent
* China PMI expands at fastest pace in more than two years
SHANGHAI, Dec 1 (Reuters) - Hong Kong stocks rose to a three-week high on Thursday morning as energy sector rallied after OPEC agreed to a deal to reduce production, while markets in China rebounded after a survey showed factory activity picked up speed last month.
The benchmark Hang Seng index added 0.7 percent by lunch break, to 22,946.07 points, while the Hong Kong China Enterprises Index gained 1.1 percent, to 9,947.48.
China's blue-chip CSI300 index erased Wednesday's loss and added 0.6 percent, to 3,559.87 points at the end of the morning session, while the Shanghai Composite Index gained 0.5 percent, to 3,267.08 points.
Zhang Qi, analyst at Haitong Securities in Shanghai, said markets cheered an oil price surge and expects China's under-valued blue-chips to be in favour in the long run.
The world's largest oil exporters agreed on Wednesday to cut output for the first time in eight years to ease a global supply glut that had halved the value of a barrel of crude.
Oil price climbed over 10 percent after the OPEC deal.
Energy shares in both Hong Kong and China's stock markets jumped, rising over 4 percent and 1.6 percent respectively. Shares of index heavyweight CNOOC Ltd soared over 6 percent by midday.
In China, investor confidence was boosted by better-than-expected manufacturing data. The official Purchasing Managers' Index (PMI) stood at 51.7 in November, accelerating from previous month's 51.2 and above the 50-point mark that separates growth from contraction on a monthly basis.
Most sector in China and Hong Kong gained. Transport shares in China, which opened 0.5 percent lower on worries higher oil prices would add to costs, turned up to end the morning session 1 percent higher after the strong manufacturing survey.
Shares in China's leading appliances maker Gree Electric Appliances shot up over 8 percent in the morning, after Foresea Life Insurance, a unit of Chinese financial conglomerate Baoneng, raised its stake in the company by more than 3 percent.
Reporting by Jackie Cai and John Ruwitch; Editing by Shri Navaratnam