"Since this morning's London open we have noted a systematic offer across most of the metals as some mean reversion type systems kick in," Marex's Alastair Munro said from the LME desk.

"And copper faces the distinct possibility of worker trouble at Escondida, the world's largest mine, over the next week or two."

Gold was similar to the point yesterday, at US$1,798 an ounce on the spot market, as investors await the outcome of the US Federal Reserve's Federal Open Market Committee policy statement later today.

Noront Resources (TSXV: NOT) was a standout in Toronto, soaring 69% to C55c on a bid from BHP which improves on an earlier offer from Australia-based Andrew Forrest's Wyloo Metals.

Noront recommended shareholders accept the BHP offer of 55c per share, which represented a 69% premium to the previous day's close.

The company's flagship project is the nickel, copper and platinum group element deposit Eagle's Nest, which it describes as the largest high-grade nickel discovery in Canada since Voisey's Bay and the most advanced project in the Ring of Fire.

BHP was down 0.8% in morning Australian trade.

London's Court of Appeal had agreed on Tuesday to reopen a major lawsuit against the miner, reviving a £5-billion claim over the 2015 Samarco dam rupture that triggered Brazil's worst environmental disaster, Reuters reported.