RAPAPORT... Security guards at a Petra Diamonds mine in Tanzania swapped rubber projectiles with metal in their weapons, resulting in increased injury and death to local residents, according to new allegations by a nonprofit organization.The information contradicts Petra's claims that guards at the Williamson deposit were authorized to use only rubber bullets, UK-based Rights and Accountability in Development (RAID) said last week. Workers at Zenith Security, Petra's contractor, received a combination of rubber and metal projectiles, and sometimes mixed both types in the same cartridge, RAID explained, citing a guard's testimony.While rubber bullets can injure and kill, they are not supposed to penetrate, whereas removing metal pellets from someone's body requires an operation, the NGO pointed out. They can cause death if the victim is close to the gun, it added.The accusations build on recent claims of violence at Williamson, including that security guards shot and beat residents. Last year, RAID said it had documented at least seven deaths and 41 assaults by security workers since Petra acquired the mine in 2009.Petra said it took the "allegations of human rights abuses at the Williamson mine extremely seriously," and noted that its ongoing investigation into events at the site was already addressing the claims RAID mentioned. The company has postponed publishing a report on the matter until the end of April - instead of March - after obtaining new information about the allegations, it continued."Deliberately altering ammunition to cause indiscriminate injury, even death, to local residents raises serious questions about Petra Diamonds' oversight of security at its diamond mine in Tanzania," said RAID executive director Anneke Van Woudenberg. "The company's claims that its gems are ethically sourced [are] completely in tatters."Image: The Williamson mine. (Petra Diamonds)