* Zinc, aluminium also hit lowest since mid December
* LME/ShFE arb: http://bit.ly/2wZSAEz
* GRAPHIC-2018 asset returns: http://tmsnrt.rs/2jvdmXl (Updates prices)
LONDON, March 21 (Reuters) - Copper steadied off an earlier three-month low on Wednesday as traders took to the sidelines ahead of a policy statement from the Federal Reserve, which is expected to detail a further increase in U.S. interest rates.
Expectations for a rate hike, along with worries over the prospect of a global trade war, earlier stoked concerns over the demand outlook for industrial metals, sending copper, aluminium and zinc to their lowest since mid December.
Markets are also awaiting guidance on whether three or four rate increases 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 at $6,760 a tonne at 1507 GMT, up 0.1 percent and off an earlier three-month low of $6,702.
* 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 labour contract, an industry group said.
* ALUMINIUM PRICES: LME aluminium slid to its lowest since mid-December at $2,062.50 a tonne. It was last bid at $2,077 a tonne, little changed from Tuesday.
* ALUMINIUM: Global primary aluminium 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 1.1 percent at $3,238 a tonne, having earlier touched a three-month low of $3,183, while lead was 1.3 percent higher at $2,382.50 a tonne. Nickel was down 0.3 percent at $13,415 a tonne, and tin was up 0.4 percent at $20,750.
(Additional reporting by Tom Daly in Beijing Editing by Louise Heavens and Mark Potter)