Tanzanian President John Magufuli has ordered a review of a local contract belonging to Petra Diamonds.
Reuters reports that he also asked senior public officials to resign over the outcome of a probe into the mining sector.
Minister of State in the President’s Office George Simbachawene had since relinquished his post, according to media reports in Tanzania.
“I have endorsed all the recommendations of the parliamentary probe committees for the review of the Williamson diamond mine contract,” Magufuli was quoted as saying in a televised broadcast.
Petra had a 75 percent stake in the mine, while the government owns the rest.
The East Africa country initially had a 50 percent stake in the company and a parliamentary committee said there were “gross irregularities” in the manner in which government lowered its shares.
The president also said that he had ordered law enforcement agencies to investigate allegations of under-declared diamond exports, which was a continuation of a crackdown in the mining sector since his election late in 2015.
Tanzania has passed new laws to increase mining taxes, to force companies to renegotiate their contracts and to allow the state to own up to 50 percent of shares in mining companies.
Meanwhile, Reuters reports that another parliamentary committee that investigated tanzanite mining said there was massive smuggling of the purple-blue gemstone.
The committee said its investigation exposed that Tanzania had received just 5.2 percent of revenues from global tanzanite trade over the past decade.
“It’s unacceptable that we have been getting just 5.2 percent of tanzanite revenues as a nation ... this is shameful,” Magufuli said.
“I am instructing our law enforcement agencies to swiftly investigate all these allegations contained in these reports against these public officials ... we cannot be truly independent if our natural resources are being plundered.”