Updates prices at 1610 GMT
By Pratima Desai and Amy Lv
LONDON/BEIJING, Aug 20 (Reuters) - Copper prices slipped on Wednesday to their lowest in nearly two weeks as funds sold, while consumers and producers were sidelined ahead of a speech by U.S. Federal Reserve Chair Jerome Powell later this week, metal traders said.
Commodity and financial markets will be looking for clues in Powell's speech on Friday as to whether U.S. be cut by 25 basis points as expected at the Fed's September 16-17 meeting, which could undermine the dollar.
A lower U.S. currency could help boost demand for dollar-priced metals. This relationship is used by funds which trade, often on a day-to-day basis, using buy and sell signals from numerical models.
Benchmark copper on the London Metal Exchange dipped to $9,670.50, its lowest since August 7, before reversing to trade up 0.3% at $9,724 by 1610 GMT as the after U.S. President Donald Trump called for the resignation of Federal Reserve Governor Lisa Cook.
"Systematic flows are dominating our space amid lack of wider involvement," said Alastair Munro, senior base metals strategist at Marex.
"Markets are struggling to move meaningfully in either direction as the outlook remains unclear."
Further out worries about demand, particularly in top consumer China, have pushed the discount for the cash copper contract over the three-month forward towards $100 a ton, the highest since February.
Also suggesting sluggish demand is the Yangshan copper premium , a gauge of China's appetite for importing copper. At $51 a ton it is up from $29 a ton on July 8 but still about half the $100 a ton seen in May.
On the technical front, upside resistance is around $9,475 a ton, where the 21- and 50-day moving averages are converging.
Traders said funds had also been selling aluminium, which briefly broke below the 200-day moving average, currently at $2,565 a ton.
Three-month aluminium earlier touched a two-week low at $2,558 a ton. It was last up 0.7% at $2,581.
In other metals, zinc gained 0.6% to $2,784.50, lead advanced 0.4% to $1,982, tin retreated 0.3% to $33,755 and nickel rose 0.2% to $15,030 a ton.
(Reporting by Pratima Desai, Amy Lv and Lewis Jackson. Editing by Harikrishnan Nair and Mark Potter, Elaine Hardcastle)
((pratima.desai@thomsonreuters.com [pratima.desai@thomsonreuters.com]))
