Copper prices slipped to their lowest in more than two weeks on Tuesday, driven down by concerns that a weak Chinese economy is curbing demand in the world's biggest metals consumer.

Three-month copper on the London Metal Exchange slid 2.3% to $8,975 a metric ton in official open-outcry trading for its weakest since Aug. 15.

Recent data from China showed that manufacturing activity sank to a six-month low in August and growth in new home prices slowed in August.

China's factories and crisis-hit property sector are major consumers of copper and other industrial metals.

"People are focusing once again on some of the weaknesses and fundamentals. China isn't growing strongly and the macroeconomic backdrop is clearly weak," said WisdomTree commodity strategist Nitesh Shah.

"China is in a holding pattern right now. It's waiting for the Federal Reserve to cut rates, which will give the green light to the PBOC to do a much more broad-based monetary easing," he said, referring to the U.S. and Chinese central banks.

Goldman Sachs cut its 2025 copper price forecast sharply on Monday, projecting an average price of $10,100 a ton, down from its previous forecast of $15,000. "We believe that copper inventory depletion - and its accompanying price rally - will likely come much later than we previously thought," it said.

Also weighing on metals was a two-week high for the dollar index. A stronger U.S. currency makes dollar-priced metals more expensive for buyers using other currencies.

LME zinc fell 1.3% to $2,803 a ton, having climbed by more than 8% in August as supply concerns helped it to register its best monthly gain since April.

Disappointing Chinese data, particularly from the construction sector, is likely to result in further price declines for zinc in the next few weeks, said Sandeep Daga, a director at Metal Intelligence Centre. Zinc is largely used to galvanise steel.

Among other metals, LME aluminium lost 0.8% to $2,404.50 a ton, nickel fell 0.8% at $16,500 and lead was also down 0.8% at $2,042.50 while tin shed 1.6% to $30,890 after touching its weakest in nearly four weeks.

($1 = 7.1149 yuan)

(Reporting by Eric Onstad Additional reporting by Mai Nguyen in Hanoi Editing by David Goodman)