According to a senior investigator into DRC operations the Kabakongoh Mining Corporation in the DRC was headed up by Bredenkamp and Rautenbach.
Bredenkamp, who was born in South Africa but who is currently in the UK, was identified as an arms dealer by the United Nations in 2002.
He was also accused of exploiting Africa's natural resources - although he denied it.
At the time he was thought to have amassed a personal fortune of about R12bn. He was then the 33rd richest person in the UK. At the moment he lives in a house next door to Britain's former prime minister Margaret Thatcher.
The source, who asked to remain anonymous because "matters were extremely sensitive" said he came across "at least eight" vehicles belonging to Rautenbach at the DRC/Zambia border post.
"I spoke to each one of the drivers of the trucks and each one confirmed they worked for Rautenbach."
He said that each truck carried the name and logo SABOT ? which is one of Rautenbach's companies. SABOT stands for South Africa/Botswana.
"Each truck was loaded with cobalt, which according to the drivers, was destined for South Africa."
"Further enquiries revealed that this cobalt was to be shipped to China and to Switzerland where I was told 'the big buyers sit'. One of these buyers is a man who was known to be 'a sanction buster' in the apartheid era and who brought oil to South Africa, despite world sanctions."
This information backs up claims by Frans van den Heever from Deloitte, a liquidator involved in Hyundai a few years ago. Last week he said that Rautenbach was actively mining cobalt in the DRC after being prohibited from doing so four years ago. He also said his main buyers were in Switzerland and that "the large part of Hyundai's money is on the British Virgin Islands".
However, Rautenbach's legal representatives in London and in South Africa denied all allegations against him on Wednesday and said he was in Zimbabwe conducting "legitimate business".