Prodeco said the violations themselves took place years earlier, before it acquired and ran the network of mines.

A Goldman spokesman said the violations resulted from a processing error and had no financial effect on clients.

Regulators said the violations occurred from 2001 to 2008.

AmerisourceBergen said the violations occurred from 2005 until 2014.

Xstrata had to pay the fines during its temporary ownership in 2009, but said the violations occurred before it took over.

But Maxwell said the violations should not prevent Mukoko from being prosecuted but rather there should be a separate inquiry to investigate the allegations.

It said the violations resulted in overcharging and client losses of approximately $472,000 and additional revenue to Barclays of more than $3.1 million.