SHANGHAI, Oct 11 (Reuters) - Chinese blue-chip companies edged up on Monday, as coal firms were lifted by supply fears and real estate shares gained on some cities’ planned supportive measures. ** The blue-chip CSI300 index rose 0.1% to 4,936.19, while the Shanghai Composite Index ended flat at 3,591.71 points. ** The coal sub-index surged 4.1% amid short supply, which led to China’s worst power crunch in years. ** China has ordered its two top coal regions to boost output and will allow coal-fired power utilities to charge customers higher prices. ** Citic Securities said it would take time for the measures to take effect and estimated the supply crunch situation is hard to be reversed this year. ** Real estate firms and banks gained more than 2% each. ** Harbin has become one of the first cities in China to announce measures to support property developers and their projects, and analysts expected some other cities will follow suit. ** A sub-index tracking defence stocks rose 1.9%. ** Chinese President Xi Jinping vowed on Saturday to achieve “peaceful reunification” with Taiwan, while the Chinese-claimed island responded by calling on Beijing to abandon its coercion. ** Talks between Indian and Chinese military commanders to resolve a protracted standoff on a stretch of disputed Himalayan border have broken down, with both sides blaming each other on Monday. ** The environmental governance sub-index lost 3.4%, while the construction engineering sub-index shed 2.8%. (Reporting by Shanghai Newsroom; Editing by Amy Caren Daniel) Our Standards: The Thomson Reuters Trust Principles.