LONDON, March 22 (Reuters) - Aluminium prices rose on Monday to their highest level since June 2018 as investors worried that Chinese efforts to reduce smelter pollution will restrict output and supply will fall short of demand.

Benchmark aluminium on the London Metal Exchange (LME) was up 0.3% at $2,273 a tonne at 1705 GMT after reaching $2,289.50.

China accounts for around 60% of global aluminium output but the government is expected to curtail capacity growth, with Inner Mongolia ordering some smelter closures this month.

"If you get production capped in the world's biggest producer and demand increasing then hopes of a more balanced market in the next few years don't look very likely (to be realised)," said independent analyst Robin Bhar.

OUTLOOK: Analysts say soaring shipping costs, booming demand and tight supplies of primary and scrap aluminium are likely to fuel further price rises, particularly in importing countries such as the United States and Europe.

COLUMN: The aluminium market has been rattled by signs of "green" disruption in China, writes Reuters columnist Andy Home.

HONGQIAO: China Hongqiao Group, a big producer, will this year publish targets for lower carbon emissions and an action plan on how to reach them, its chairman said.

DEMAND: "We expect global demand to outpace supply growth by 0.3% in 2021 increasing to 2.9% in 2022, which should start to see aluminium inventories drawing down," said analysts at RBC.

SUPPLY: Global primary aluminium output fell to 5.203 million tonnes in February from a revised 5.727 million tonnes in January, data from the International Aluminium Institute (IAI) showed.

POSITIONING: Speculative investors are rebuilding a bullish position in LME aluminium with a net long equal to 7.8% of open contracts as of Thursday, brokers Marex Spectron said.

STOCKS: On-warrant aluminium inventories in LME-registered warehouses surged from 1.1 million tonnes to a five-year high of 1.7 million tonnes earlier this month but have quickly fallen back to around 1.2 million tonnes.

CHINA SCRAP: China's scrap metal and refined aluminium imports rose sharply year-on-year in January and February. [nL4N2LG527}

PRICES: LME copper was up 0.3% at $9,088 a tonne, zinc rose 1.3% to $2,875 a tonne, nickel added 0.8% at $16,435, lead gained 1% at $1,978.50 and tin was up 0.9% at $25,900.

(Reporting by Peter Hobson Additional reporting by Mai Nguyen; Editing by Susan Fenton, Louise Heavens and Richard Chang)