Petra Diamonds (LSE: PDL) said on Monday it had halted operations at its Williamson mine in Tanzania after a tailings storage facility burst, causing flooding in nearby areas.
The company, which also operates three mines in South Africa, said the eastern wall of Williamson's tailing dam was "breached," but said in an email that the pit was not affected.
Petra noted that there were no injuries or fatalities confirmed so far, adding that the government and mine emergency response teams had been mobilized to the site.
"While no injuries have been reported, any impact on the local communities would be viewed as a material negative from an ESG standpoint," Berenberg bank analysts said in a note.
The diamond miner has worked hard to clean its image in Tanzania. Last year, it achieved a ?4.3 million (about US$4.9 million) settlement with claimants alleging widespread human rights abuses, including beatings and detentions, at Williamson - the country's biggest diamond mine.
Petra, which has repeatedly denied the involvement of its own employees in the incidents, admitted that "regrettable" incidents took place at the mine in the past.
The clashes between locals and police resulted in "the loss of life, injury and the mistreatment of illegal diggers" within the mining licence, it said last year.