Rebels in the eastern Democratic Republic of Congo have consolidated control over the Rubaya coltan-mining region, imposing a production tax estimated to generate around $300,000 in monthly revenue, the United Nations Security Council heard on Monday.

The M23 movement, a Tutsi-led organization purportedly backed by Rwanda, seized the area, which produces minerals used in smartphones and computers, following intense fighting in April.

Bintou Keita, head of the U.N. mission in Congo, told the Security Council that trade from minerals in the Rubaya area accounts for over 15% of global tantalum supply.

Congo is the world's top producer of tantalum which is considered a critical mineral by the United States and the European Union.

"This generates an estimated $300,000 in revenue per month to the armed group," Keita said. "This is deeply concerning and needs to be stopped."

"The criminal laundering of the DRC's natural resources smuggled out of the country is strengthening armed groups, sustaining the exploitation of civilian populations, some of them reduced to de-facto slavery, and undermining peace-making efforts," Keita added.

The majority of Congo's mineral resources are situated in the east, a region plagued by conflict over land and resources between several armed factions. The situation has deteriorated since the resurgence of the M23 rebellion in March 2022.

Thousands have been killed and over 1 million displaced since the resurgence in fighting.

Manufacturers are under scrutiny to ensure that metals used in products such as laptops and batteries for electric vehicles are not sourced from conflict zones like eastern Congo.

Keita said that as profits from mining have surged, armed groups have become militarized entrepreneurs, making them stronger both militarily and financially.

"Unless international sanctions are imposed on those benefiting from this criminal trade, peace will remain elusive, and civilians will continue to suffer," Keita said.