Dec 6 (Reuters) - London copper erased earlier gains to fall on Monday, pressured by a stronger dollar and uncertainty over the economic impact of the Omicron coronavirus variant.

Three-month copper on the London Metal Exchange fell 0.2% to $9,397 a tonne, as of 0800 GMT, while the most-traded January copper contract on the Shanghai Futures Exchange closed down 0.2% at 69,080 yuan ($10,841.18) a tonne.

"Everyone is still sort of adjusting their positions and selling off any longs they've been having... The dollar has been strengthening given the tapering has been brought forward and people are still trying to figure out how bad this Omicron variant could be," a Singapore-based trader said.

The dollar index was up 0.2%, making the greenback-denominated commodity more expensive for those holding other currencies.

However, declines were limited by supply concerns exacerbated by MMG Ltd's decision to shut down production at its Las Bambas copper mine in Peru by mid-December.

Stockpiles of the metal, widely used in power, manufacturing and infrastructure sectors, dropped to a record 169,599 tonnes in Chinese bonded warehouses last week.

On-warrant LME copper inventories were at 70,275 tonnes, down over 70% from August highs. ShFE stockpiles fell to 36,110 tonnes last week, down 84% from May's 229,179 tonnes.

Logistics and supply chain bottlenecks have led to low copper inventories in some regions, while there might be traders building invisible stockpiles betting on a bullish copper outlook, said CRU analyst He Tianyu.

FUNDAMENTALS

* Speculators cut their net long positions on copper on COMEX to 13,382 contracts, as of Nov. 30, latest exchange data showed, the lowest since Aug. 24. They boosted short positions to 39,240, the highest since June 15.

* LME aluminium fell 1.1% to $2,594 a tonne, zinc was down 1.5% to $3,117, nickel was 1.9% lower at $19,655 a tonne and tin slipped 3% to $38,150 a tonne.

* ShFE aluminium fell 0.5% to 18,710 yuan a tonne, nickel shed 2.1% to 145,660 yuan a tonne, zinc was down 1.5% at 22,725 yuan a tonne, lead fell 2.6% to 14,820 yuan a tonne and tin dropped 3.3% to 276,410 yuan a tonne.

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($1 = 6.3720 Chinese yuan)

(Reporting by Eileen Soreng in Bengaluru and Mai Nguyen in Hanoi; Editing by Devika Syamnath and Subhranshu Sahu)