Copper prices fell in London on Monday with some investors booking profit as the metal was on track for its biggest monthly gain since April after a series of stimulus measures in top metals consumer China.

Three-month copper on the London Metal Exchange (LME) was down 0.8% at $9,905.5 per metric ton in official open-outcry trading after hitting $10,158, its highest since June 7. The metal, used in power and construction, is up 7.6% so far in September.

China's central bank said on Sunday it would tell banks to lower mortgage rates for existing home loans before Oct. 31, as part of sweeping policies to support the country's beleaguered property market.

Chinese stocks surged on Monday, and China's yuan posted its biggest quarterly gain against the dollar since 2020, making dollar-priced metals more attractive for buyers using this currency.

U.S. Comex copper futures touched $4.7900 a lb, the highest since May 28, before retreating to $4.5825, down 0.4% vs Friday.

"It seems like traders got a bit carried away, especially in New York, perhaps expressing a market where liquidity is poor ahead of the China's Golden Week holiday and LME Week in London," said Ole Hansen, head of commodity strategy at Saxo Bank.

LME Week, the annual gathering of metals industry participants in London, started on Monday. The calendar end of the quarter, when some investors square their books, coincides on Monday with the last trading day in China before the week-long Golden Week holiday.

Copper is yet to show signs of actual physical demand improving to sustain the positive momentum from China's stimulus package, Hansen added.

In terms of long-term prospects, mining giant BHP said the world would consume an extra 1 million tons of copper a year on average until 2035, double the annual volume growth in the past 15 years.

LME nickel rose 1.8% to $17,300 in official activity, zinc increased 0.6% to $3,109, lead lost 0.1% to $2,116.5 and tin climbed 1.2% to $33,300, while aluminium eased 1.1% to $2,617.5 a ton.

Zinc, nickel and tin prices touched multi-month highs.

(Reporting by Polina Devitt in London; additional reporting by Mai Nguyen in Hanoi; Editing by David Evans and Krishna Chandra Eluri)