The London Metal Exchange has found bags full of stones at one of its warehouses instead of the nickel they were supposed to contain in the latest drama to hit the scandal-stricken metals market.

The exchange said in a notice to the market on Friday that it had “received information that a number of physical nickel shipments, out of one specific facility of an LME-licensed warehouse operator, have been subject to such irregularities”. The supposed nickel consignments were actually filled with stone, said a person familiar with the matter.

The LME added that the irregularities in the bagged nickel were “evident, from among other things, by the weight of the bags” and it “reminds licensed warehouse operators of the strict requirement to weigh all metal before it is placed” into the exchange’s approved warehouses.