By Summer Zhen

HONG KONG, Aug 12 (Reuters) - China stocks climbed, while Hong Kong shares remained steady on Tuesday, as the extension of tariff truce between the United States and China, the world's two largest economies, helped cushion investor sentiment.

** Washington and Beijing on Monday extended a tariff truce by 90 days, staving off triple-digit duties on Chinese goods, in a decision that markets had widely expected.

** China's blue-chip CSI300 Index .CSI300 climbed 0.6% by the lunch break, while the Shanghai Composite Index .SSEC gained 0.51%.

** Hong Kong's benchmark Hang Seng .HSI was steady at 24,929.34 by midday.

** "This is not a surprise to the financial markets. Investors already assumed the deadline would be extended," said Zhiwei Zhang, chief economist at Pinpoint Asset Management.

** The trade negotiation will take months and investors have shifted their focus to the U.S.-Russia summit, which could have important implications for the financial markets, he added.

** China markets have been trending higher in recent weeks, as investors priced in positive signals from the U.S.-China trade talks in Geneva, London and Stockholm, which focused on bringing retaliatory tariffs down from triple-digit levels.

** China's blue-chip stocks .CSI300 have gained 15% and Hong Kong's Hang Seng .HSI are up 7% since early April when U.S. President Donald Trump first announced the duties.

** Semiconductor stocks .CSI931865 lifted mainland A-shares on Tuesday, with Wafer Works (Shanghai) 688584.SS and Cambricon Technologies 688256.SS up 20% and 16%, respectively.

** On chip sale restrictions, Trump on Monday suggested he might allow Nvidia to sell a scaled-down version of its next-generation advanced GPU chip in China.

** Some investors remained cautious on China stocks even as the immediate concerns over tariff had eased.

** Ben Bennett, Asia head of investment strategy at L&G Asset Management said they are neutral on Chinese equities.

** "We don't think the government will provide significant extra stimulus in the coming months, but would stand ready if the U.S. turns up its tariff pressure," he said.

** "It's largely a stalemate situation where the can is being kicked down the road for further trade negotiations," said Moh Siong Sim, a currency strategist at Bank of Singapore.

(Reporting by Summer Zhen, additional reporting by Ankur Banerjee; Editing by Sherry Jacob-Phillips)

((summer.zhen@thomsonreuters.com; 852-3462-7739;))