In an investigation over 18 months the BBC has found evidence that United Nations peacekeepers in the Democratic Republic of Congo supplied weapons to notorious militia.
Panorama: Mission Impossible on BBC One at 8.30pm on Monday 28 April 2008.
Worse still, there are indications that the UN covered up what was taking place for political reasons.
The story began in December 2005 in the gold mining town of Mongbwalu, in eastern Congo.
The town had changed hands several times, as rival ethnic militia fought to control the rich resource.
Human Rights Watch found evidence that the UN's Pakistani peacekeepers in the mining town of Mongbwalu had traded in gold with militia operating in the area - the FNI.
The Pakistanis also facilitated the work of Kenyan based gold traders, who were illegally flown into the town on UN aircraft.
UN insiders the BBC has spoken to tell us this aspect of the UN report was suppressed for political reasons
The UN began looking into what had taken place and soon came across allegations of arms being provided to the FNI by the Pakistanis.
The Pakistan Army has denied the allegations.
When UN investigators attempted to pursue their enquiries, the Pakistani troops in Mongbwalu surrounded the mission station in which they were staying, and confined the military police accompanying the investigators behind barbed wire.
Finally the UN produced a report, finding one Pakistani major responsible for the gold trading, but could not substantiate the allegations that weapons and ammunition were supplied to the FNI "in the absence of corroborative evidence".
The UN's Alan Doss responds to the allegations
The head of UN peacekeeping operations in New York - Jean-Marie Guehenno - was questioned about the allegations. This is what he had to say.
"The investigation has found no evidence of gun smuggling. But it has identified an individual who seemed to have facilitated gold smuggling.
"We have shared the report with the concerned troop contributing country and I am confident they will take the required action. And this issue is closed."
But new evidence uncovered by the BBC throws this into doubt.
"An FNI militant says he saw seven boxes of ammunition being transported from the Pakistani base to re-supply FNI militia during a key battle."
"A leading member of a rival militia - the UPC - says he knew the Pakistanis were re-arming the FNI"
This was confirmed by a miners leader.
Arms and ammunition
The BBC has also visited the two key FNI leaders, known as Kung Fu and Dragon, in the maximum security prison in the capital, Kinshasa where they are being held.
Both confirmed that they did, indeed receive arms and ammunition from the UN troops. They made a statement to this effect, prior to the UN report on the subject, but were never questioned about this statement by the UN investigators.
"A senior Congolese army officer said that FNI militia he had disarmed were seen the next day with the same weapons - a statement not referred to in the UN's own report.
"An interpreter who sat in during discussions about the weapons between the Pakistanis and the FNI.
UN insiders the BBC has spoken to tell us this aspect of the UN report was suppressed for political reasons - it was simply too difficult to accuse Pakistan of re-arming known killers, since Pakistan is the largest troop contributor to the UN, providing 10,000 troops across the world.
These allegations were put to the head of the UN's internal investigation branch, the Office of Internal Oversight Services.
She is a Swede, Inga Britt Ahlenius. When questioned about this she told the BBC she still stood by the investigation.
Jean-Marie Guehenno: No evidence of arms smuggling.
"It is several months since I read the final report. And I don't recall any details as you mention now and I am not in a position to defend the investigators, that they should have interviewed this person or that person.
"And I feel confident that they draw the conclusions on the evidence that they had been able to retrieve and based the report on that.
"But I would suggest you contact our investigators, and maybe they can re-open the case."
Pakistan has responded by saying that there is no evidence that its troops were involved in an illegal gold trade or re-armed militia, describing the allegations as baseless.
At the same time Pakistan says that three of its officers have been disciplined for failing to live up to the high standards expected of its military.
The Indian Army told Panorama that an investigation by the UN watchdog had revealed that all but one of the allegations were based on hearsay or had no credible evidence.
Panorama: Mission Impossible, BBC One at 8.30pm on Monday 28 April 2008