At midweek, copper was up 2% to $5458.25 per tonne, the highest price since March 11.
"With a total of 462,000t at the end of May, inventories are some 20% below the historical average for May, in China stock remain elevated versus historical levels - 24% above normal for May despite large outflows," VTB Capital head of metals and mining research Dmitry Glushakov said.
"We believe that Chinese inventory data reflects the stock accumulation within the copper supply chain in anticipation of stronger economic recovery in the country in the second half of 2020."
Likewise, tin also gained 2% to $15,818.25/t, the highest point since March 13.
Zinc and nickel were also near pandemic-highs.
Comex gold futures were slightly weaker at $1750 an ounce at midweek, as US stocks rose despite civil unrest.
Silver rose to $18.83/oz, the highest level since February.
BMO Capital Markets increased its long-run gold forecast by 16.7% to $1400/oz, and its long-run silver forecast by 5.8% to $18.25/oz.