* GRAPHIC-2018 asset returns: http://tmsnrt.rs/2jvdmXl
* LME/ShFE arb: http://bit.ly/2wZSAEz (Adds more analyst comment, updates prices, changes dateline from BEIJING)
LONDON, Jan 23 (Reuters) - Copper prices fell to the lowest in a month on Tuesday after inventories surged, showing healthy supplies of refined metal.
On-warrant copper stocks - metal not earmarked for delivery from warehouses and available for investors - in facilities certified by the London Metal Exchange <MCUSTX-TOTAL> jumped by 28 percent on Tuesday, data showed.
"I don't perceive any particular tightness in the cathode market whatsoever. Premiums are going lower and I don't think anyone is concerned about availability," said analyst Vivienne Lloyd at Macquarie in London.
LME prices, however, would see decent support in the first half of the year, Lloyd added, due to worries about potential disruptions stemming from the expiry of labour contracts at some copper mines and restrictions on scrap metals into China.
"With this mine (labour) news you've got upside risk, and the scrap side of the market is still very disrupted," she said.
* LME COPPER: Three-month LME copper was down 1.8 percent at $6,937 a tonne by 1105 GMT, the weakest since Dec. 20.
* COPPER SCRAP: China's imports of scrap copper fell 19.8 percent in December from a year earlier, customs data showed on Tuesday, as the country continues a clampdown on taking foreign waste.
* COPPER DEFICIT: The global deficit of refined copper narrowed in October to 2,000 tonnes from 113,000 tonnes in September, the International Copper Study Group said in its latest monthly bulletin.
* USD: Base metals were weighed down by a firmer dollar index, with some investors judging that the currency's recent decline to a three-year low may be coming to a close amid concern over the U.S. stance on global trade.
* LEAD STOCKS: On-warrant LME lead inventories <MPBSTX-TOTAL> fell 5,000 tonnes or 6 percent to 80,000 tonnes, indicating lack of short-term supply. They are approaching lows from late March of 77,800 tonnes, the weakest since June 2013.
LME lead shed 0.7 percent to $2,600.50 a tonne.
* ALUMINIUM: LME aluminium dropped 1.5 percent to $2,216.50 a tonne.
The copper/aluminium ratio had declined to 3.143 by Monday's close, the tightest seen since Oct. 10, Alastair Munro at broker Marex Spectron said in a note.
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(Additional reporting by Tom Daly in Beijing; Editing by Dale Hudson)