The Democratic Republic of Congo's state-owned mining company Gecamines on Monday accused its foreign partners of "stealing" after its book-keeping was challenged by US and British reports.
"For the past 15 years our partners have... cheated us and stolen from us. That must stop," said Albert Yuma, chairman of the board and a close associate of President Joseph Kabila.
In July, the British NGO Global Witness described the Congolese mining sector as a "cash machine" for Joseph Kabila's regime, which has been in power since 2001.
And in early November American NGO the Carter Center estimated that a total of $750 million (644 million euros), generated by the mining production between 2011 and 2014, "cannot be reliably traced" in the Gecamines accounts.
The US foundation suggested Gecamines used "its privileged position to generate $1.1 billion (937 million euros) from copper and cobalt deals between 2011 and 2014" yet had failed to reliably account for almost two-thirds of the revenue.
"It's an idiocy, it's a lie, it's incompetence," said Yuma to company executives in Lubumbashi, the DR Congo's second largest city.
"All the money has been recorded in the accounts of Gecamines. Not a dollar is missing and most of this money has gone into the staff, investments and financing of the Congolese state.
"The state should have received 768 million dollars in taxes, but the state has got none, because our partners have always arranged for the operating accounts to be lost year by year," he added.
He said he had asked accountancy firm Ernst & Young to "rethink" the organisation of Gecamines to better control foreign partnerships.
According to him, the challenge for the DR Congo is to take control of its minerals, "as 40 years ago our Arab brothers benefited from the control of their oil".
The DR Congo produces cobalt, which according to Yuma is "the most sought-after material in the world".
"The next world war will fight over the control of cobalt," he said.