The Democratic Republic of Congo may increase state participation in mining projects to 35 percent from 5 percent and raise royalties on mineral exports, according to a preparatory report obtained by the country’s business association.

The 35 percent stake would be acquired for free and could not be diluted, according to the report, which was prepared for an inter-ministerial commission charged with updating Congo’s 10-year-old mining code. The Mines Ministry declined to comment on the proposals, while the country’s business association, known by its French acronym FEC, criticized them.

“We feel abandoned and we were not consulted” on the proposed revisions, Simon Tuma-Waku, the national vice president in charge of mines for the FEC, said in a phone interview yesterday. “What’s important for investors is the fiscal regime and stability and we think this shouldn’t be modified because right now it’s very attractive for investors.”

Congo is the world’s largest cobalt producer and was the tenth-largest exporter of copper last year, according to CRU Group, a London-based research company. The Central African nation, which is nearly the size of Western Europe, also has deposits of gold, iron, diamonds, tin and coltan.