JOHANNESBURG - Insecurity around Société Minière de Bisunzu's (SMB) coltan mine in Democratic Republic of Congo could get worse if it is cut out of supply chains following a deadly grenade attack there, the company running the mine's mineral tracing scheme said.

Up to three people were reported killed in the attack on June 23 in Kisura village, which is on an unmined part of SMB's vast mining concession known as PE 4731.

SMB, which has some of Africa's largest deposits of the tantalum-rich ore coltan, has been using a digital tracing system since January 2019 to show its minerals are not mined by children or fund warlords and corrupt soldiers.

The system, called the "Better Sourcing Program" (BSP), is run by Berlin-based RCS Global.

"A disengagement from purchasing PE 4731 material, or for mining activities to stop, would be hugely detrimental to the security in the area and could worsen tensions, as occurred in 2018 when mining activity was temporarily suspended," RCS Global said.

"DRC government and international stakeholder engagement will be beneficial to move the underlying tensions towards resolution," RCS Global said in a statement due to be released to smelters and stakeholders on Monday.

Tantalum is used in electronic goods such as smartphones, laptops and video game consoles. Companies that use the mineral are under pressure from regulators and investors to show the metals have been sourced responsibly.

SMB and the mineworkers cooperative which works on the site have given diverging accounts of what happened in the attack last month. Miners accused police hired by SMB of using excessive force, which SMB and the police deny.

In its statement, RCS Global said SMB was in the process of implementing a series of corrective actions it had recommended to address concerns about SMB's supply chain following the incident.

These included training mine police on the respect of voluntary principles on security and human rights, engaging with provincial bodies, and requesting support from national authorities.

BSP, which has four full-time monitoring agents on SMB's concession, said it was unclear who launched the grenade attack.

SMB said last month that two policemen were targeted in a nighttime grenade attack, which was followed by gunfire. Three people were killed and three, including one policeman, were hurt and taken to hospital, it said.