Zenith Security guards employed at diamond miner Petra Diamonds’ Williamson mine, in Tanzania, allegedly deliberately swapped rubber projectiles with metal shot in their weapons, causing serious harm to local residents shot on the company’s concession, UK corporate watchdog RAID said in a statement on March 25.

Moreover, the watchdog said the guards were also issued with metal projectiles in contrast to what senior management said was its policy.

The information uncovered by RAID was part of ongoing research into alleged human rights abuses at the Williamson mine since UK-listed company Petra Diamonds took ownership in 2009.