LONDON, Jan 23 (Reuters) – Copper prices fell to their lowest in a month on Tuesday after rising inventories showed healthy supplies of refined metal. Lead, however, climbed to the highest since 2011 after stocks declined. On-warrant copper stocks – metal not earmarked for delivery from warehouses and available for investors – in facilities certified by the London Metal Exchange 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 closed 2.1 percent weaker at $6,923 a tonne, 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. * DOLLAR: Base metals got support from a weaker dollar index , which slipped to a fresh three-year low after data showed euro zone consumer confidence jumped much more than expected in January. * LEAD STOCKS: On-warrant LME lead inventories 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. * LEAD: LME lead climbed to an intraday peak of $2,636.50 a tonne, the strongest since August 2011, but gave up its gains and closed down 0.4 percent at $2,610. * ALUMINIUM: LME aluminium ended down 0.9 percent at $2,229.50 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.