* LME lead stocks hit highest since June 2018
* Lead price sinks to one-month low (Updates with official prices, ECB decision)
LONDON, Sept 10 (Reuters) - Copper prices slipped on Thursday as investors questioned whether its recent rally was exaggerated and were cautious ahead of a news conference by the European Central Bank (ECB).
Copper, which has rebounded about 50% from 45-month lows in March, is the best-performing industrial metal this year, helped by a recovery in top metals consumer China and tumbling inventories.
Three-month copper on the London Metal Exchange fell 0.7% to $6,684.50 a tonne in official trading, after rising on Wednesday.
LME copper inventories MCUSTX-TOTAL ticked higher on Thursday after repeatedly touching the lowest levels since 2005 in recent weeks.
“That raised the question of whether for copper we have priced in most of the supportive news in terms of declining stocks and Chinese data. That leaves the market somewhat focused on what happens on the macro front,” said Ole Hansen, head of commodity strategy at Saxo Bank in Copenhagen.
“Having failed above $6,800, the really big number for copper is the uptrend from the March low and that’s coming in at $6,550, which if broken could add additional selling pressure.”
* The ECB left policy unchanged, but investors will scrutinise a news conference, which could set the stage for further stimulus.
* Benchmark treatment charges for copper concentrate next year are likely to fall for a sixth straight year to their lowest since 2011 at about $60 a tonne.
* LME lead inventories MPBSTX-TOTAL rose to 131,750 tonnes, the highest since June 2018, having more than doubled over the past two months.
The discount of LME lead cash to the three-month contract CMPB0-3 rose to $28.75 a tonne, the highest since November 2018, indicating healthy supplies.
* LME aluminium edged down 0.2% to $1,781 a tonne in official activity, nickel fell 0.8% to $14,796 and tin added 0.1% to $18,025.
Lead dropped 0.6% to a one-month low of $1,882.50 while zinc lost 0.6% to $2,409.50 after touching $2,385, the weakest in over three weeks. (Additional reporting by Enrico Dela Cruz in Manila; Editing by Mark Potter)
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