SHANGHAI, March 24 (Reuters) - China and Hong Kong stocks were largely flat on Monday as investors grew cautious with U.S. President Donald Trump's tariff deadline approaching and no new market stimulus in sight.

** China's blue-chip CSI300 Index .CSI300 edged up 0.2% by the lunch break, while the Shanghai Composite Index .SSEC lost 0.3%. Hong Kong benchmark Hang Seng .HSI was down 0.1%.

** U.S. President Donald Trump's top trade chief, Jamieson Greer, plans to speak with his Chinese counterpart this week, ahead of the long-threatened April 2 unveiling of fresh U.S. tariffs on countries taxing U.S. imports, potentially including new steps against China. Market participants are watching closely for tariff headlines.

** Meanwhile, U.S. Republican Senator Steve Daines met Chinese Premier Li Qiang in Beijing with a group of executives from U.S. companies on Sunday, following an annual business summit in the capital attended by CEOs from big foreign firms.

** "The ongoing US-China tensions may erode external demand, sap domestic investment, squeeze manufacturers' margins, and dent workers' pay," said Ting Lu, chief China economist at Nomura.

** As growth could face much stronger headwinds in the second half of the year, Lu expects Beijing to be pressured into increasing stimulus measures to stabilise growth, particularly in service consumption.

** China's central bank reiterated its stance to cut banks' reserve requirement ratio and interest rates at an "appropriate time" during a quarterly meeting of its monetary policy committee.

** Wall Street firm Morgan Stanley MS.N raised its 2025 GDP growth forecast for China by 50 basis points to 4.5%, citing the impact of stimulus measures on local governments and consumption that have started to filter through "leading to green shoots".

** Non-ferrous metals shares .CSISNMIM rose 1.5% in China, while property shares .CSI000952 dropped 1.1%.

** Sentiment for Hong Kong tech majors .HSTECH stayed downbeat, with shares slipping 0.2%.

(Reporting by Shanghai Newsroom; Editing by Mrigank Dhaniwala)

((li.gu@tr.com))