SHANGHAI, Aug 1 (Reuters) - Mainland China and Hong Kong stocks extended their losses on Friday and looked set for a losing week, weighed by soft domestic economic data and worries over global trade following U.S. President Donald Trump's new tariffs.

** At the midday break, the Shanghai Composite index .SSEC was down 0.19% at 3,566.55 points, while the blue-chip CSI300 index .CSI300 fell 0.25%.

** If both indexes retain losses at the market close, they will book their first weekly drop in six.

** In Hong Kong, the Hang Seng Index .HSI slipped 0.18% to 24,727.78 points, while the Hang Seng China Enterprises Index .HSCE lost 0.01% to 8,882.04 points.

** Trump slapped steep tariffs on exports from dozens of trading partners, pressing ahead with his plans to reorder the global economy ahead of a Friday trade deal deadline.

** "The U.S. deals with other economies will also affect China's trade outlook," economists at ANZ said in a note on Friday.

"If the U.S. fully enforces around 20% tariffs and 40% transshipment tariffs on ASEAN, which accounted for 17.8% of China's exports in the first half of this year, the supply chain activity in the region will be strained."

** Meanwhile, the United States believes it has the makings of a trade deal with China, but it is "not 100% done," U.S. Treasury Secretary Scott Bessent said on Thursday.

** China's factory activity contracted in July, both official and private surveys showed, suggesting the economy lost momentum following robust growth in the first half of the year.

** "After a more resilient than expected trade environment in the first half of 2025, momentum could soften a bit further in July," said Lynn Song, chief economist for Greater China at ING, noting market attention will be shifted to trade data due next Thursday for more clues on the health of the broad economy.

** Around the region, MSCI's Asia ex-Japan stock index .MIAPJ0000PUS was weaker by 0.94% while Japan's Nikkei index .N225 was down 0.44%.

(Reporting by Shanghai Newsroom)