The IMF reduced its forecast for world economic growth this year to 3.3 percent from 3.5 percent previously, citing the US-China trade war and a potentially disorderly British exit from the European Union.
It warned chances of further cuts to the outlook were high.
Meanwhile, the US Trade Representative on Monday proposed slapping tariffs on a list of EU products ranging from large commercial aircraft to dairy products and wine as it kicked off the retaliation process against European aircraft subsidies.
A stronger US dollar on Wednesday also weighed on prices for dollar-denominated metals as it makes them more expensive for countries using other currencies to make purchases.
FUNDAMENTALS
COPPER: Three-month copper on the London Metal Exchange had fallen 0.1 percent to $6,483.5 a tonne by 0357 GMT, while the most active copper contract on the Shanghai Futures Exchange was down 0.1 percent at 49,550 yuan ($7,381.86) a tonne.
RESISTANCE: "The previous (copper) prices were a little high," said Shanghai-based copper analyst He Tianyu of CRU.
London copper hit $6,540 in the previous session, its strongest since April 1, with He saying that had been a resistance level since February and that he had not seen any signs of a pick up in demand.
PERU: An indigenous community in Peru voted to suspend its two-month road blockade of MMG Ltd's Las Bambas copper mine for two days until the government visits the region on Thursday, an advisor to the community told Reuters.
PRICES: London aluminium dipped 0.1 percent, while zinc climbed 0.3 percent and lead rose 0.5 percent. Shanghai zinc was on track for its third straight decline, down 0.7 percent, and lead was down 0.7 percent.