By Thomas Fessy
The BBC has evidence that Gen Gabriel Amisi Kumba installed a mining firm at the Omate mine in return for a 25% cut.
Following a mining ban in September, production is continuing at the mine under direct military control.
The general refused to answer questions about his role and the firm involved, Geminaco, denies there was a deal.
The lure of profits from mines in eastern DR Congo has turned the area into a battlefield.
Rebels target civilians in the surrounding villages near the border with Rwanda and Uganda and there have been reports of kidnapping, massacres and mass rapes, fuelled by the profits from minerals.
The military was sent in to suppress the rebels and ensure security for the local people.
Raw gold
During the last 12 months, Geminaco approached Gen Amisi, the second in command of the army, asking him to help it take over Omate.
Rene Mwinyi, head of Geminaco, told the BBC the company had the rights to mine the area.
In February, the general wrote to the regional army commander in North Kivu, telling him to evict a rival company, Socagrimines, in favour of Geminaco.
The BBC has a copy of the letter, which says: "I order you to proceed to the eviction of the administration in place and all military involved in mining activities and to reinstate Geminaco in its initial positions."
But the head of the government's mining division in North Kivu, Emmanuel Ndimubanzi, said the general should have had no role in the dispute between the two companies.
He added that neither Socagrimines nor Geminaco had the right to mine at Omate.
A well-placed source in the industry told the BBC the general benefited from the arrangement.
"The head of Geminaco in Congo, Rene Mwinyi, is a friend of General Amisi, or 'Tango Fort' as they call him," he said.
"They struck a deal to exploit Omate gold mine, which would give Amisi 25% of the monthly production of the raw gold."
A soldier, who spent over two months at the mine, also told the BBC: "At Omate there is the company Geminaco which exploits the minerals... and there are also soldiers who were sent by our chief of staff, General Tango Fort, who are also mining."
"The gold goes to the brigade commander in charge of units which are supposed to hunt down rebels...it also goes to Kinshasa. This is very serious: Instead of benefiting the state, this money goes to unknown pockets."
Mr Mwinyi said no such deal was done with Gen Amisi.
However, the 25% arrangement was confirmed by a provincial government source. Like many of the people who spoke to me, he would not go on the record because of fear of reprisals.
A source at Socagrimines said the company had tried and failed to do a deal with Gen Amisi itself. He said it was impossible to mine in the area without military support.
'Soldiers desert posts'
In September, Congolese President Joseph Kabila ordered a ban on mineral production in the east of the country, to root out what he called "mafia groups" who control the trade.
It is part of efforts by the UN and government to make the industry more transparent - initiatives include new trading guidelines and the setting up of mineral exchange centres.
Geminaco has since been evicted from Omate, and its manager at the mine was arrested in October.
A source told the BBC that the manager was arrested because Gen Amisi was not getting his promised cut of the profits. The manager himself denied there was any deal between the company and the general.
He said Geminaco's ejection from the mine was related to the ban - which contradicts Mr Mwinyi's statement that the firm has an exemption from it.
Despite the ban, mining has continued at Omate - now under direct control of the military.
A gold digger confirmed that he was working at the Omate mine very recently. Armed soldiers control the mine and often beat the diggers, he said.
I was unable to visit the mine myself because of the heavy deployment of soldiers. However, a friend visited on foot and confirmed that production is continuing.
When the BBC contacted Gen Amisi, he refused to answer questions about Omate, saying he was not entitled to talk to the media.
He referred us to the army's spokesman who said we had no authority to investigate the general's interests.
DR Congo remains one of the world's poorest countries, despite its rich resources of minerals like gold, cassiterite and coltan.
The east of the country was ravaged by many years of war involving Congolese, Ugandan and Rwandan forces.
An estimated five million people died and the area has suffered continuing conflict involving armed groups who have committed numerous atrocities.
Just this summer, more than 300 civilians were raped in this area by a coalition of rebel groups.
An internal memo from the UN peacekeeping mission in DR Congo suggested that the villages attacked were vulnerable because there were no Congolese soldiers to protect them.
The soldiers deployed there had left their posts to go to mining areas nearby, including Omate.
