The Investigative Committee, a branch of the Prosecutor General's Office, said Storchak allegedly belongs to a group that planned to steal tens of millions of dollars from the government, The Moscow Times reported Monday.
Storchak, who works closely under Finance Minister Alexei Kudrin, is in charge of the country's $148 billion oil stabilization fund.
Vladimir Markin, spokesman for the Investigative Committee, said Storchak was arrested with a businessman and a bank director "on suspicion of attempting to embezzle large sums from the state budget."
Kudrin, attending a conference in South Africa, defended his aide. He said Storchak "everyday struggled for every kopek, for every cent, defending the interests of Russia in all debt negotiations."
"I don't yet understand these charges, which I will, of course, study in detail," Kudrin said. "I think that the finance minister's opinion of this situation will be taken into consideration."