China shares slide as investors await trade deal signing

* Shanghai shares fall 0.5%, blue-chips down 0.6%

* China to ramp up U.S. buys under Phase 1 trade deal - source

* U.S. to keep tariffs on China until Phase 2 deal - Mnuchin

HONG KONG, Jan 15 (Reuters) - The Chinese stock market fell on Wednesday, just hours before the world’s largest economies are set to sign a Phase 1 trade deal, as the U.S. Treasury Secretary insisted that tariffs will stay in place.

** At the close, the Shanghai Composite index was 0.5% weaker at 3,090.04, while the blue-chip CSI300 index lost 0.6%. ** CSI300’s financial sector sub-index fell 1%, the consumer staples sector edged up 0.5%, the real estate index was down 1.7% and the healthcare sub-index gained 0.3%. ** The smaller Shenzhen index fell 0.2% and the start-up board ChiNext Composite index inched up 0.1%. ** The United States will maintain tariffs on Chinese goods until the completion of a second phase of a U.S.-China trade agreement, U.S. Treasury Secretary Steven Mnuchin said on Tuesday. ** That took some steam off Chinese shares, which rallied on Tuesday after the U.S. Treasury withdrew its designation of China as a currency manipulator in a major de-escalation of the 18-month long Sino-U.S. trade conflict. ** Trump is set to sign the Phase 1 trade deal with Chinese Vice Premier Liu He at the White House on Wednesday at 11:30 a.m. (1630 GMT). ** Under the Phase 1 trade deal, China would also buy over $50 billion more in energy supplies and boost purchases of U.S. services by about $35 billion over the same period, a source, who was briefed on the deal, told Reuters late on Monday. ** Commodity traders and analysts are struggling to map out how China will reach the eye-popping amounts it is committing to buy from the U.S. without threatening trade ties with other suppliers, hurting its own domestic producers, and making substantial changes to import standards and quotas. ** Shares in China’s car makers, rare earths-related firms and agricultural companies dropped on Tuesday. ** Around the region, MSCI’s Asia ex-Japan stock index was weaker by 0.4%, while Japan’s Nikkei index closed down 0.5%. ** The largest percentage losses in the Shanghai index were ButOne Information Corporation XiAn and Ningbo Shenglong Automotive Powertrain System Co Ltd, down 10%, followed by Liaoning Shidai Wanheng Co Ltd, down by 9.9%. ** So far this month, the Shanghai stock index is up 1.3%, having risen 6.2% in December. The CSI300 has gained 1.7% this month, and was up almost 7% in December. ** About 20.23 billion shares were traded on the Shanghai exchange. The volume in the previous trading session was close to 23 billion. ** The Shanghai stock index is above its 50-day moving average and above its 200-day moving average. (Reporting by Noah Sin; Editing by Shailesh Kuber)