The London Metal Exchange (LME) discovered “irregularities” with bagged nickel briquettes at one of its warehouses this week, which forced it to postpone a resumption of trading in the metal during Asian hours until March 27.

According to a statement from the LME, it had to cancel nine nickel warrants at one of its facilities after finding out that bagged nickel briquettes stored there were found to not have the weight specified in the contracts.

“The exchange has 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 exchange said in the statement.