The report accepts there may be a contradiction in the UN mandate
UN-backed operations against rebels in eastern Democratic Republic of Congo have failed, a leaked report says.
The document, seen by the BBC, says mineral resources are being plundered with impunity and there has been a new surge of rapes and killings.
It says UN forces supporting Congolese government troops have failed to stop supply lines to Rwandan-Hutu rebels.
The report, written by UN-mandated experts, will be discussed by the UN Security Council later.
The BBC's East Africa correspondent Peter Greste says in many ways the report vindicates rights groups who have been criticising the Congolese government offensive against the rebels, known as the Democratic Forces for the Liberation of Rwanda (FDLR).
'Crisis made worse'
BBC News, East Africa
The people behind the leak are clearly worried enough about the UN's willingness to adopt its recommendations to pass the report to the press.
This is not the first report by a UN group of experts. The last one published a year ago came up with strikingly similar recommendations.
If nothing was done to implement those recommendations the first time around, there are good reasons for insiders to suspect that nothing will be done this time.
On its own, the report will not resolve the complex mess in DR Congo, but the people who handed it to the BBC believe that if the UN takes it seriously, it can make a significant difference.
The UN has actively supported the operation as a way of stopping one of the most feared militias in a very bad neighbourhood, our correspondent says.
But the leaked report says: "Military operations have not succeeded in neutralising the FDLR and have exacerbated the humanitarian crisis."
Jason Stearns, a DR Congo analyst, called the conclusions of the report "astounding".
He told the BBC's Network Africa programme the group had concluded there was a "complete lack of transparency" in the mineral trade in DR Congo.
"This allows many actors to continue to buy tin and gold from areas controlled by rebel groups - thereby financing these rebels groups," he said.
"They have implicated some of the most important gold dealers in DR Congo, in Burundi and in Rwanda - these are very high level officials involved in this."
The report says FDLR rebels - some of whose leaders were involved in the Rwandan genocide - have been able to use vast international networks to bolster their supply of arms and recruit extra soldiers.
And it says the Rwandan fighters are also supported by senior members of the Congolese military - the very people who are supposed to be fighting them.
It says the Congolese army has factions within it operating effectively as separate militias.
'Terminator' at large
One such group, under the leadership of former warlord Gen Bosco Ntaganda, has expanded its influence since the military operation began earlier this year and unleashed a wave of killings, rapes and looting.
WHO'S WHO IN THE EAST
FLDR: Rwandan Hutu militia, controls gold and tin mining areas - 6,000-8,000 fighters
CNDP: Tutsi-led group, former rebels under command of Bosco Ntaganda now integrated into the army, but accused of operating as a parallel militia - 6,000 men
Monuc: 18,000 UN peacekeepers nationwide
Congolese army: 50,000 soldiers in east (Circa 100,000 nationwide)
Sources: UN Group of Experts/UN/military experts
Gen Ntaganda, known as "the Terminator", is wanted by the International Criminal Court for alleged forced enrolment of child soldiers in 2002-2003.
He formerly served in a militia known as the Congress for the Defence of the People (CNDP) but joined the national army at the beginning of this year.
The report found that Gen Ntaganda's men were deployed in some of the region's most lucrative mining areas, which they now control.
The BBC's Thomas Fessy, in Kinshasa, says the report's authors recognise that there may well be a contradiction in the mandate of Monuc, the UN's peacekeeping mission in DR Congo, of protecting civilians and backing the military.
Our correspondent says the report casts doubt on whether it is possible to ensure civilians are safe while providing logistical support to an army which continues to perpetrate rights abuses.
He says Monuc's mandate is up for renewal at the end of the year and it will be interesting to see how the Security Council takes all this information into account.
It has already voted twice to continue the peacekeeping support for the operations despite opposition from human rights groups and aid agencies.
ALLEGATIONS IN REPORT BY UN EXPERTS
Supplying arms to FDLR; high-level contact between the rebels, Tanzanian government and military
High-level contact between government and FDLR
Burundi and Uganda
Conduits for FDLR to traffic gold to the United Arab Emirates
Cassiterite smuggling centre; former CNDP rebels in contact with Kigali businessmen
Sudan and North Korea
Irregular deliveries of arms to DR Congo
Links between leaders in Europe, North America and commanders on the ground; money-laundering in South Kivu 's illegal minerals export trade