METALS-Copper slips to 3-month low ahead of Fed policy statement

* Zinc, aluminum also hit lowest since mid December

* LME/ShFE arb: http://bit.ly/2wZSAEz

* GRAPHIC-2018 asset returns: http://tmsnrt.rs/2jvdmXl (Updates throughout, adds LONDON dateline)

LONDON, March 21 (Reuters) - Copper slid to three-month lows on Wednesday along with zinc and aluminum as expectations for another U.S. interest rate hike and worries over the prospect of a global trade war stoked concerns over the demand outlook for industrial metals.

Copper, chiefly used in construction, is down for a fifth session on the London Metal Exchange, ahead of the Federal Reserve's decision on U.S. interest rates later.

Markets are expecting the Fed to announce a quarter-point hike after European markets close, but are awaiting guidance on whether three or four are planned for 2018 as a whole.

"(We believe) there will be a rate hike in the short term, and of course that's not positive for base metals," ABN Amro analyst Casper Burgering said.

"It's really macroeconomic events that are giving prices direction. We will have to wait for some good fundamental news before we see prices increase again."

Traders are also bracing for further news from the United States on trade, with U.S. President Donald Trump expected to announce up to $60 billion in new tariffs on Chinese imports by the end of the week.

* LME COPPER: Three-month copper on the London Metal Exchange was down 0.3 percent at $6,734 a tonne at 1030 GMT, having earlier touched a three-month low of $6,712.

* FINANCIAL MARKETS: European stocks eased and the dollar retreated from three-week highs as investors marked time before a likely hike in U.S. interest rates.

COPPER SURPLUS: The global world refined copper market showed a 17,000 tonnes surplus in December, compared with a 41,000 tonnes deficit in November, the International Copper Study Group said in its monthly bulletin.

* LOS PELAMBRES: Workers at Antofagasta PLC's Los Pelambres copper mine in Chile have opted to extend a period of government mediation in an effort to reach agreement on a new labor contract, an industry group said.

* ALUMINIUM PRICES: LME aluminum slid to its lowest since mid-December at $2,062.50 a tonne, and was later at $2,075 a tonne, down 0.1 percent.

* ALUMINIUM: Global primary aluminum output excluding China dipped to 2.009 million tonnes in February from a revised 2.221 million tonnes in January, International Aluminium Institute (IAI) data showed on Tuesday.

* OTHER METALS: LME zinc was up 0.9 percent at $3,231 a tonne, off an earlier three-month low of $3,183, while lead was 1 percent higher at $2,376 a tonne. Nickel was down 0.3 percent at $13,420 a tonne, and tin was flat at $20,675.

(Additional reporting by Tom Daly in Beijing Editing by Robin Pomeroy)