LONDON – Copper slumped to a one-month low as a large delivery of metal into exchange warehouses in Asia refocused attention on demand during a seasonally weak period for industrial activity in China.

Prices fell as much as 2.6% to $6,885 a ton on the London Metal Exchange as inventories tracked by the bourse jumped by the most in ten months, continuing a pattern of spikes and drawdowns in LME inventories seen throughout 2017.

The delivery comes as manufacturers in China prepare to dial back output during the week-long Lunar New Year holiday next month, and adds to evidence that copper demand is hitting a soft patch often seen at this time of year, according to Robin Bhar, an analyst at Societe Generale.

“The funds had taken prices to increasingly rarefied levels which weren’t justified by the fundamentals,” Bhar said by phone from London, adding that physical premiums paid by buyers in China have also slipped in recent weeks. “The market probably knew this delivery was on its way, and now we’re seeing it being incorporated into the price.”

The red metal fell 2.1% to settle at $6 923/t at 5:51 pm in London, extending a three-week tumble. Copper futures for March delivery dropped 2.7% to $3.11/lb at 1:05 pm on the Comex, in New York, the lowest settlement since December.

Copper “may see more sideways-to-downward movement in the short run,” Andrew Cosgrove, the senior analyst of energy and mining equities at Bloomberg Intelligence, said in a note Tuesday. “While a weakening US dollar has helped, a relief rally or stabilisation in the interim may remove a tailwind the red metal’s enjoyed.”

There’s “strong support” at $6 600, he added.

Analysts are warning that cracks are beginning to appear in the bull case for industrial metals. Aluminium dropped 0.9% Tuesday on the LME, while zinc, lead and tin also fell. Nickel edged higher. Iron-ore also slumped back towards $70/t, suffering the biggest rout since December on signs that declining profitability in China’s steel sector is denting demand.