(Adds comment, detail, updates prices) MELBOURNE, May 19 (Reuters) - London copper was set for a weekly gain on Friday as dollar weakness cushioned prices, but the outlook was tainted by investors cutting exposure to metals on China demand concerns. "Base metals slumped as the political crisis in the U.S. threatened to delay the infrastructure spending plans and tax cuts that President Trump has promised. Economic data in China didn't help quell fears about weaker demand," said ANZ in a report. "This has seen investors become increasingly bearish. The net long positions of non-commercial traders on both the LME and Comex have been falling over the past few weeks and are now at levels last seen before the Trump trade rally started."
* LME COPPER: London Metal Exchange copper edged up down 0.5 percent in the previous session when prices hit their lowest in more than a week at $5,485 a tonne. Prices were set for a small weekly gain of 0.8 percent. Support is seen at the 200-day moving average around $5,400.
* SHFE COPPER: Shanghai Futures Exchange copper ended the session up 0.4 percent at 45,300 yuan ($6,573) a tonne.
* DOLLAR: The dollar recovered from six-month lows against a basket of currencies on Friday, but remained lower on the week amid political turmoil in the United States. A weaker dollar makes commodities cheaper for buyers paying with other currencies.
* U.S. ECONOMY: The probability that the U.S. economy will grow 3 percent this year has fallen over the last month as weak data and political concerns have dented confidence, according to a slim majority of economists in a Reuters poll.
* CHINA INVESTORS: China investors have cut metals holdings since President Xi Jinping called for increased efforts to ward off systemic risks to help maintain financial security last month. China's April non-financial outbound direct investment (ODI) fell 71 percent from a year earlier to $5.82 billion.
* CHINA ZINC: Premiums for zinc in China jumped by $10 to $155 a tonne, the highest in nearly three years, as the gap between local and global prices turned favorable for imports.
* CHINA ZINC: China is likely to step up imports of refined zinc from this month, industry sources said on Friday, as dwindling global supplies of concentrate hit local output of the metal, used to galvanize steel.
* LME LEAD: was on track for a 7.8 percent monthly drop in May on rising supply after stocks in China surged above 80,000 tonnes to the highest since March 2014. <PB-STX-SGH> PRICES
BASE METALS PRICES 0712 GMT Three month LME copper 5599 Most active ShFE copper 45290 Three month LME aluminum 1921 Most active ShFE aluminum 14025 Three month LME zinc 2534 Most active ShFE zinc 21430 Three month LME lead 2072 Most active ShFE lead 15365 Three month LME nickel 9160 Most active ShFE nickel 75990 Three month LME tin 20295 Most active ShFE tin 144040
BASE METALS ARBITRAGE
LME/SHFE COPPER LMESHFCUc3 199.93 LME/SHFE ALUMINIUM LMESHFALc3 -1387.14 LME/SHFE ZINC LMESHFZNc3 451.23 LME/SHFE LEAD LMESHFPBc3 -1649.42 LME/SHFE NICKEL LMESHFNIc3 1305.66
($1 = 6.8931 Chinese yuan renminbi)
($1 = 6.8915 Chinese yuan renminbi)
(Reporting by Melanie Burton; Editing by Miral Fahmy)