(Reuters)-Rwanda’s defense minister is commanding a rebellion in eastern Democratic Republic of Congo that is being armed by Rwanda and Uganda, who also sent troops to aid the insurgency in a deadly attack on U.N. peacekeepers, according to a U.N. report.

The U.N. Security Council’s Group of Experts said in a confidential report that Rwanda and Uganda, despite their denials, continued to support M23 rebels in their six-month fight against Congolese government troops.

The 44-page report, seen by Reuters on Tuesday, said M23 has expanded territory under its control, stepped up recruitment of child soldiers and summarily executed recruits and prisoners.

“The Government of Rwanda continues to violate the (U.N.) arms embargo through direct military support to M23 rebels, facilitation of recruitment, encouragement and facilitation of FARDC (Congolese army) desertions as well as the provision of arms and ammunition, intelligence, and political advice,” said the report, which was seen in full by Reuters.

Uganda and Rwanda have denied the allegations.

“M23’s de facto chain of command includes General Bosco Ntaganda and culminates with the Rwandan Minister of Defence General James Kabarebe,” said the experts, who monitor compliance with U.N. sanctions and an arms embargo on the Congo.

Ntaganda, a former Congolese army general who has been nicknamed “Terminator”, is wanted by the International Criminal Court in The Hague for war crimes, including the recruitment of child soldiers.

The report added that M23 had expanded its control of Rutshuru Territory with extensive foreign support in July 2012 and had taken advantage of a recent informal ceasefire “to expand alliances and command proxy operations elsewhere.”

Nearly half a million people have been displaced due to the fighting between M23 and Congolese army. M23 has proven so resilient that one senior U.N. diplomatic source told Reuters privately that Rwanda has effectively “annexed” mineral-rich eastern Congo thanks to the rebel force.

The rebellion also is being funded by traders in Rwanda who are profiting from tin, tungsten and tantalum smuggled across the border from mines in the eastern DRC, according to the report.

An interim report from the Group of Experts that was published in June raised similar accusations against Rwanda but with far less detail. Kigali was furious about that report, saying it was one-side and contained false allegations.

Rwanda has backed armed movements in the neighboring DRC, during the past two decades, citing a need to tackle Rwandan rebels operating out of Congo’s eastern hills.

HEAVY WEAPONS FOR M23

The experts, whose report was delivered earlier this month to the Security Council’s Congo sanctions committee, also accused Uganda of providing vital support to the rebels.

“Senior Government of Uganda officials have also provided support to M23 in the form of direct troop reinforcements in DRC (Congo) territory, weapons deliveries, technical assistance, joint planning, political advice and facilitation of external relations,” the report said.

The experts said that units of the Ugandan and Rwandan armies “jointly supported M23 in a series of attacks in July 2012 to take over the major towns in Rutshuru Territory, and the (Congolese army) base of Rumangabo.”

During these attacks, the rebels killed a U.N. peacekeeper and fired on a U.N. peacekeeping base at Kiwanja.

“According to several M23 soldiers, RDF (Rwandan army) troops provided the rebels with heavy weapons such as 12.7 mm machine guns, 60 mm, 91 mm and 120 mm mortars, as well as anti-tank and anti-aircraft launchers ahead of the attack,” the report said.

“RDF Special Forces in Rutshuru also aided the rebels and fired 13 rounds on a FARDC (Congolese army) combat helicopter during the takeover of Kiwanja,” it said.

Ugandan military spokesman Felix Kulayigye rejected the report.

“Where’s the evidence for their claims? Some of those so-called experts came here and did not interview anyone,” he said. “Where’s their authentic facts to back those claims? Those accusations are absolute rubbish, hogwash.”

Olivier Nduhungirehe, senior Rwandan diplomat at the country’s U.N. mission, had a similar denial, which he sent to Reuters on Sunday. He said the experts have been “allowed to pursue a political agenda that has nothing to do with getting at the true causes of conflict in the eastern DRC.”

Rwandan President Paul Kagame reiterated Rwanda’s denials at a high-level meeting in New York last month that both he and Congolese President Joseph Kabila attended.

The Group of Experts said that it has corroborated its findings on Rwanda’s involvement with multiple intelligence sources.

“Various South African Development Community (SADC), European, Ugandan, and Burundian intelligence agents also confirmed the group’s findings concerning Rwandan violations of the (arms) embargo,” the report said.

It added that the Rwandans have stepped up recruitment for M23, which the report said had around 1,250 soldiers in Rwanda.

“RDF (Rwandan army) recruitment for M23 within Rwanda has increased in the past four months,” it said. “The main targets for recruitment are Rwandan demobilized soldiers and civilians, as well as Congolese refugees.”

“The use and recruitment of child soldiers by armed groups, notably by M23, has increased,” the report said, adding that over 250 children had been recruited. “Furthermore, certain M23 commanders have ordered the extrajudicial executions of dozens of recruits and prisoners of war.”

“M23 uses boys on the frontlines as cover for advancing units, often after a week of training,” the experts said. “Others act as porters, intelligence operatives and bodyguards. The rebels use young girls as cooks and as commanders’ wives.”