LONDON, Dec 31 (Reuters) - Industrial metals ended 2021 posting their biggest annual price gains since 2009 driven by tight supply and increased demand and led by aluminium and tin.

Prices were mixed on Friday, with trading muted during the Christmas holiday season.

The London Metal Exchange (LME) index, made up of copper, aluminium, nickel, zinc, lead and tin, was up 32% in 2021 after rising 20% in 2020.

"It's been a year with strong demand recovery from the pandemic," said ING analyst Wenyu Yao. "Most metals markets flipped into deficit."

"Looking into 2022, we expect it's a year of normalisation. We expect demand growth to moderate," she said, adding that limited supply should keep prices high, at least in the near term.

PRICES: Benchmark copper on the LME closed up 0.3% at $9,720.50 a tonne and up 25% in 2021, having risen 26% in 2020.

LME aluminium fell 0.4% to $2,807.50 a tonne on Friday but was up 42% in 2021, its biggest gain since 2009.

Zinc was flat at $3,534 but for the year was up 28.5% higher in its biggest jump since 2017.

Nickel was 0.8% higher at $20,757 on Friday and up 25% this year, its largest annual rise since 2019.

Lead rose 0.3% to $2,304 and was up 15% in 2021, its biggest gain since 2017.

Tin was down 0.9% at $38,860 a tonne. For 2021, it was up more than 90%, the largest annual gain in at least two decades.

RALLIES: Other commodities also surged in 2021 and global stock markets were on track for a third consecutive year of double-digit gains.

CHINA: China's factory activity unexpectedly accelerated in December, but analysts see trouble ahead.

"China has been a primary source of demand for base metals since 2003, but we think this trend has started to come to an end," said Justin Smirk, an economist at Westpac.

"With the decline of investment and production as key growth drivers, this will see diminishing incremental economic growth and a reduction in materials demand as a share of output," he said.

PERU: The operators of the Las Bambas copper mine in Peru said it would restart operations after reaching a deal with protesters blocking a road to the mine.

CHILE: Copper output in Chile, the world's largest producer, fell 1.6% year-on-year in November.

(Reporting by Peter Hobson; Additional reporting by Enrico Dela Cruz in Manila; editing by Jan Harvey and Jason Neely)