SHANGHAI, May 25 (Reuters) - China stocks seesawed on Wednesday and edged up at midday break, as traders mulled over authorities' economic support promises and a slowing growth outlook as China continues to grapple with the spread of COVID-19.

The CSI300 index rose 0.2% to 3,965.84 points after dropping as much as 0.3% earlier, while the Shanghai Composite Index gained 0.6%, to 3,088.66 points.

The Hang Seng index added 0.6%, to 20,240.98 points. The Hong Kong China Enterprises Index gained 0.5%, to 6,920.63.

** As COVID-19 outbreaks and stringent anti-virus measures dragged, global investment banks have slashed their China 2022 GDP growth outlooks to as low as 3%, marking a huge discrepancy from the government's target of around 5.5%.

** China's financial regulators pledged to keep credit growth stable in the property sector and help homebuyers affected by COVID-19 outbreaks to defer mortgage payments, and the central bank said it would use various tools to appropriately increase credit and support economic growth.

** China reported 590 new coronavirus cases for Tuesday, down from 688 new cases a day earlier.

** Energy and transport shares went up 2% each, while property developers edged down 0.3% and liquor makers lost 1.6%.

** Rising geopolitical tensions also dented risk appetite, as Russian and Chinese bombers flew joint patrols near Japanese and South Korea air defense zones on Tuesday in a pointed farewell to U.S. President Joe Biden as he concluded a trip to Asia that rankled Beijing.

** U.S. Secretary of State Antony Blinken will deliver a speech on Thursday outlining U.S. policy toward China, the State Department said.

** Tech giants listed in Hong Kong rose 0.7% after falling as much as 1% in morning trade, with Alibaba down 1% ahead of its earning result on Thursday, while Meituan gained 1%.

** "Significant issues remain" in reaching a deal with China over a audit dispute of China companies listed in the United States, a U.S. Securities and Exchange Commission (SEC) official said on Tuesday.

(Reporting by Shanghai Newsroom)