Russia's Investigative Committee said Tuesday it had detained Economy Minister Alexei Ulyukayev on suspicion of taking a two-million-dollar bribe over a massive deal involving state-controlled oil giant Rosneft.
The committee, the country's main federal investigative body, said the move was a result of an operation by the FSB security service, the successor to the KGB.
It alleged in a statement the minister received the money on Monday for giving the go-ahead for Rosneft to acquire a majority stake from the state in Russian oil company Bashneft in a $5.2 billion (4.84 billion euro) deal last month.
The statement does not say who gave the alleged bribe to Ulyukayev.
The sale of the 50.07 percent stake in Russia's sixth-largest producer came after months of wrangling that has seen Rosneft -- headed by Igor Sechin, a powerful ally of President Vladimir Putin -- face down opposition from some in the government, while Ulyukayev said Rosneft could bid for the stake.
"The entire sum -- 329.69 billion rubles -- will go to the Russian budget," Ulyukayev said in a statement after the deal on October 12, adding that the government had received only two bids and the other one had been less than the company's independently assessed value.
Putin said publicly at the time that he was "a little surprised at such a position of the government, but this really is the government position, primarily of the financial and economic bloc".
The Investigative Committee said Ulyukayev had been detained as part of a probe into large-scale bribe taking, for which he could face a jail term of between eight and 15 years.
It said that it will charge him shortly.
Spokeswoman Svetlana Petrenko told RIA Novosti news agency: "This is about extortion of a bribe from Rosneft representatives accompanied by threats."
"Ulyukayev was caught red-handed as he received a bribe," she said.
She said that "the acquisition of the Bashneft shares was carried out on a legal basis and is not the subject of the criminal investigation."
Ulyukayev, who has served as head of the ministry of economic development since 2013, was tasked with pulling Russia out of the longest economic crisis since Putin took power 16 years ago, sparked in late 2014 by falling oil prices and Western sanctions over Moscow's actions in Ukraine.
RIA Novosti cited a law enforcement source as saying that Ulyukayev was detained as part of a "sting operation" after investigators received "serious evidence" from "tapping his conversations and the conversations of his associates."
A spokesman for Rosneft told TASS state news agency the company would not comment on the Investigative Committee's actions but that it acquired the Bashneft stake "in accordance with Russian law on the basis of the best commercial offer made to the operating bank."