Metals-Copper slips ahead of Fed rate decision

Meanwhile, aluminium posted the biggest gain on SHFE, as the most active contract SAFcv1 closed the day 1.03% higher at 23,455 yuan a ton.

The overnight rise in SHFE aluminium appeared to be driven more by sentiment and futures positioning than stronger physical demand, said Rupankar RM, head of market research and data intelligence at AL Circle.

"The futures rally has yet to be validated by stronger physical demand," Rupankar said, adding that broader macro developments may have supported sentiment.

Its LME peer CMAL3 was up 0.46% at $3,162 a ton.

Among other LME metals, zinc CMZN3 rose 0.15%, lead CMPB3 gained 0.29%, nickel CMNI3 added 1.18% and tin CMSN3 climbed 1.09%.

Elsewhere, on the SHFE, zinc SZNcv1 dipped 0.08%, lead SPBcv1 added 0.86%, nickel SNIcv1 nudged 0.08% higher and tin SSNcv1 gained 0.72%.

($1 = 6.7693 Chinese yuan renminbi)

Copper ticked down on Wednesday, contending with demand worries and a strong dollar ahead of the conclusion of the U.S. Federal Reserve's meeting.

Benchmark three-month copper CMCU3 on the London Metal Exchange slipped 0.13% to $13,667 a metric ton by 0700 GMT.

The most-traded copper contract on the Shanghai Futures Exchange SCFcv1 closed daytime trading down 0.15% at 104,890 yuan ($15,494.96) a ton.

The Fed is expected to hold rates steady on Wednesday, though markets have raised the odds of a September increase. Traders see a 70% chance of no change this week and a 76% chance of a September hike, according to CME FedWatch.