Luzolo Bambi, a counselor to President Joseph Kabila on graft and money laundering, did not give any specifics during an interview with local radio but said corruption existed at some of the highest levels of government.
"When you have an evasion, a leak, a fraud evaluated at 10 to 15 billion ... dollars per year ... it's up to the head of state to reverse that trend," Bambi said.
Congo is Africa's leading copper producer and boasts abundant reserves of gold, diamonds and cobalt but the country ranks 186 out 187 on the U.N. Human Development Index, largely due to endemic corruption.
Congo also comes near the bottom of Transparency International's index of perceptions of corruption, coming in at 154 out of 175 countries.
Bambi filed a criminal complaint in June on behalf of Kabila against more than a dozen current and former government officials for fraud, corruption and money laundering.
He said on Wednesday that the public prosecutor's office has yet to respond to the complaint.
(Reporting by Aaron Ross; editing by David Clarke)