LONDON - Base metals prices rose in London on Thursday, supported by unexpected growth in factory activity in top metals consumer China and a vote of approval from the House of Representatives to suspend the U.S. debt ceiling.

Benchmark copper on the London Metal Exchange (LME) rose 1.7% to $8,226 a tonne in official open-outcry trading. The metal used in power and construction fell by 5.9% in May.

ING expects copper prices to remain volatile in the coming days, reacting to any policy change in China, and to average $8,500 a tonne in 2023.

"In the near term, copper prices are likely to continue to be dictated by the pace of China's economic recovery as well as the (U.S.) Fed’s interest rate hiking path," said ING analyst Ewa Manthey.

Driven by improved production and demand in China, the Caixin/S&P Global manufacturing purchasing managers' index (PMI) rose to 50.9 in May, marking a return to growth, compared with a contraction in activity seen in the official PMI on Wednesday.

In the zinc market, LME on-warrant stocks fell to 78,650 tonnes after cancellation of warrants to take delivery of 3,175 tonnes from LME-registered warehouses in Singapore.

Total LME inventories of zinc are at a one-year peak following growth since May 23, indicating a surplus of the metal used to galvanise steel.

Confidence on the LME market about availability of the metal for speedy delivery pushed the discount for the cash contract over three-month zinc to $18.75 a tonne at Wednesday's close for the deepest discount since mid-March 2022.

LME zinc gained 1.7% to $2,286 a tonne in official activity, aluminium rose 0.3% to $2,252.5, nickel edged up 1.5% to $20,900 and tin lost 0.4% to $25,350.

Lead fell by 1.1% to $1,990 after touching $1,976 for its lowest in almost seven months.

(Reporting by Polina Devitt; Additional reporting by Mai Nguyen in Hanoi Editing by Barbara Lewis and David Goodman )