SHANGHAI, Sept 4 (Reuters) - China stocks jumped on Monday, logging their best day in more than a month, as authorities stepped up measures to boost the country's faltering economy after previous stimulus policies failed to drive a sustained market rally.

** China's blue-chip CSI 300 Index closed up 1.5%, while the Shanghai Composite Index climbed 1.4%.

** Hong Kong's Hang Seng Index added 2.5% and the Hang Seng China Enterprises Index jumped 3.2%.

** All four tier-1 cities in China loosened the definition of "first-time homebuyer" to ease mortgage credit for qualified individuals. Top banks paved the way for further cuts in lending rates and sources said Beijing was planning further action including relaxing home purchase restrictions.

** "They send a clear signal that policymakers want to stabilise the property market, boost growth and lift sentiment," Goldman Sachs said in a note. "We suspect more piecemeal measures will continue to be introduced until policymakers are satisfied with the result."

** Most sectors rose in onshore markets, with energy , insurance firms and liquor makers up between 2.5% and 3.4%.

** The Beijing Stock Exchange 50 Index jumped roughly 6% and recorded its best daily performance, after the stock regulator announced reform measures.

** In Hong Kong, tech giants added 3% and mainland property developers surged 8.2%.

** Property developer Country Garden jumped 14.6% after it won approval from its creditors to extend payments for an onshore private bond.

** Foreign investors, after a record monthly net selling in August, bought a net 6.8 billion yuan ($935.14 million) of Chinese shares via the Stock Connect on Monday.

** Meanwhile, China's central government has approved setting up a special bureau within the National Development and Reform Commission (NDRC) to promote the development and growth of the private economy, the NDRC said on Monday. ($1 = 7.2716 Chinese yuan) (Reporting by Shanghai Newsroom; Editing by Sonia Cheema)