Nairobi — U.S. Secretary of State Antony Blinken said Wednesday he is very concerned about a U.N. report that says Rwanda is backing rebels in the neighboring Democratic Republic of Congo.

Concluding a two-day visit to the Democratic Republic of Congo Wednesday, U.S. Secretary of State Antony Blinken said he was disturbed by a U.N. Security Council report showing that Rwanda provided troop reinforcements for M23 rebels in eastern Congo last November.

Speaking in Congo's capital, Kinshasa, Blinken vowed to raise the matter during his imminent visit to Rwanda.

He called on all parties in the region to stop supporting the M23 rebels who are fighting the DRC government in eastern Congo. The group re-emerged in November of last year after nearly a decade of cease-fire.

The Rwandan government has denied assisting M23.

The top U.S. diplomat, who is on his second Africa tour, assured Congo of U.S. support, especially in investment, to ensure best practices are upheld. He encouraged the DRC to collaborate and work on fiscal transparency and labor rights for the mining sector.

The U.S. pledged $30 million to help the DRC promote responsible and sustainable mining practices and raised concerns about the auction of Congo's oil and gas blocks in sensitive areas.

In July, Reuters reported that licensing rights for 30 gas and oil blocks in the DRC were auctioned, opening parts of the world's second largest rainforest to drilling that could release large amounts of carbon into the air and jeopardize efforts to stem global warming.

Washington and Kinshasa agreed to form working groups on environmental impacts on oil block auctions.

Blinken heads to Rwanda late Wednesday to wrap up his visit to the African continent.