Three-month copper on the London Metal Exchange (LME) had dipped 0.1% to $8,776 a tonne by 1555 GMT, having touched $8,695 for its lowest since March 5.

“There are concerns about China deleveraging; that seems to be uppermost in a lot of people’s minds. How much more tightening is there to come? And the Chinese economy seems to be slowing anyway,” said independent consultant Robin Bhar.

Data on Thursday showed China’s March factory activity among small, private firms expanded at the slowest pace in almost a year, contrasting with another survey on Wednesday that showed stronger activity among large and state-owned manufacturers.

“Copper inventories are rising on the LME and it seems that demand for the time being has come off the boil, which is a bit concerning because we’re going into the seasonally strong part of the year,” Bhar said.

Also weighing on copper was news that Chilean state copper giant Codelco clinched a deal with workers at its Radomiro Tomic mine after they accepted a new contract offer, defusing worries about a potential strike.

The Yangshan copper premium hovered around its lowest since Dec. 23 at $58.50 a tonne, indicating weakening demand for imported copper into China. Stockpiles of the metal in exchange warehouses have been rising steadily.

Worries about aluminium supply pushed up the US physical aluminium premium to its highest since June 2019 at $416.30 a tonne while premiums in Europe reached $153.87 a tonne, a level not seen since May 2018.

LME aluminium climbed 0.9% to $2,231 a tonne.

LME zinc fell 1.3% to $2,782, lead shed 0.9% to $1,957.50, nickel gained 0.8% to $16,200 and tin gave up 0.8% to $25,175.