LONDON: Copper touched its highest in more than two years on Friday as speculators extended their buying spree on a recovery in top metals consumer China while the dollar weakened.

Benchmark copper on the London Metal Exchange (LME) hit $6,850 a tonne, its highest since June 2018, before paring gains to $6,801 in official trading for a rise of 0.3%.

Copper has surged by 55% since hitting 45-month lows in March.

"It's just phenomenal, the strong market we're seeing right now. It's really the China story and also about the overall momentum that has come into the commodities space," said Ole Hansen, head of commodity strategy at Saxo Bank in Copenhagen.

"As long as we stay above the key uptrend, which today is at $6,700, then there's no reason for the speculators, who have accumulated quite a sizeable long position in copper, to make any adjustments."

Data this week showed that China's industrial output accelerated the most for eight months in August while the OECD upgraded its economic growth outlook for China.

The dollar index eased after downbeat US data cast a shadow over the economic outlook, making it cheaper to buy metals using other currencies.

Physical premiums in China continued to ease, falling $4.50 on Friday to $59 a tonne, data showed, extending a decline from highs of $100 six weeks ago. That is the lowest level since the start of April.

China premiums are expected to fall further before seasonal demand picks up towards the end of the month, broker Triland said in a report, citing ample stocks in the country after high imports.

LME aluminium rose 0.3% to $1,785.50 a tonne in official activity, zinc gained 0.6% to $2,530 and lead was up 0.4% at $1,917.50.

In negative territory, nickel shed 0.8% to $14,963 a tonne and tin eased by 0.2% to $18,160.