* LME/ShFE arb: http://bit.ly/2wZSAEz
* GRAPHIC-2018 asset returns: http://tmsnrt.rs/2jvdmXl (Adds official midday prices, details)
LONDON, March 9 (Reuters) - Metals hit multi-month lows on Friday on concerns about escalating trade tensions after the United States announced tariffs on steel and aluminium imports.
U.S. President Donald Trump's decision to impose a 25 percent import tariff on steel and 10 percent on aluminium, with initial exemptions for Canada and Mexico, is set to take effect within 15 days.
China said it "resolutely opposed" the tariffs and that they would "seriously impact the normal order of international trade", while the EU said it will go to the World Trade Organization to impose its own measures if hit by the tariffs.
"The impact of tariffs on metals markets is small, (as is) the impact of the tariffs in terms of U.S. or global GDP. But if the tariffs spark an acceleration in trade restrictions and shave 1 or 2 percent off global GDP, that's when they become very problematic," said Bernstein analyst Paul Gait.
International Monetary Fund Managing Director Christine Lagarde said she feared a "tit-for-tat" escalation of trade retaliation that would hurt business confidence and investment.
* PRICES: Benchmark LME copper contracts traded flat in official midday rings at $6,838 a tonne, having touched a one-month low. Aluminium traded down 0.3 percent at $2,099 after hitting a 2-1/2 month low.
* ZINC: Zinc, used to galvanise steel, was hit hardest among base metals. It was last bid down 0.5 percent at $3,213 after hitting a 2-1/2 month low.
* STEEL: The most traded steel rebar contract in Shanghai slumped by 3.7 percent to a 3-1/2 month closing low.
* NICKEL: Bucking the trend, stainless steel raw material nickel traded up 0.9 percent at $13,385 after LME data showed a 13 percent slide in on-warrant stocks to 201,240 tonnes.
* ALUMINIUM STOCKS: Deliverable aluminium stocks in Shanghai Futures Exchange warehouses rose by 4,517 tonnes to a record 846,913 tonnes.
* U.S. DATA: U.S. job growth recorded its biggest increase in more than 1-1/2 years in February, but a slowdown in wage gains pointed to a gradual increase in inflation this year, weighing on the dollar and boosting commodities and equities.
* RUSAL: Russian aluminium producer Rusal said its aluminium poses no threat to U.S. firms as its products are "not produced in sufficient quantity" by U.S.-based producers.
* WIDER MARKETS: Global shares were set to end the week in the black following the U.S. jobs report and a potential breakthrough in nuclear tensions over the Korean peninsula.
* OTHER METALS: Lead was last bid up 0.5 percent at $2,348, having hit a 5-1/2 month low, while tin traded down 1.4 percent at $21,255.
(Additional reporting by Melanie Burton and Tom Daly; editing by David Goodman and Jason Neely)