The Federal Security Service (FSB) has arrested Russian Economy Minister Alexey Ulyukaev, who is accused of receiving a $2 million bribe, authorities said early Tuesday.

"Ulyukaev has been arrested while receiving a bribe. He is accused of extortion and threats to representatives of (state-run oil company) Rosneft," said spokesperson of the Russian Investigative Committee Svetlana Petrenko.

On the same morning, according to a statement issued by this authority, a criminal case was opened against the economy minister after an operation carried out by the FSB.

The secret services detained the minister on Monday while he was reportedly receiving a $2 million bribe that he had demanded from Rosneft to authorize the company's takeover of another state-owned oil company, Bashneft.

"The money was delivered to Ulyukaev during an operation monitored by FSB agents," a source close to the investigation told Interfax news agency.

According to the spokesperson, FSB agents have been monitoring the case since last summer, when they discovered that the minister threatened Rosneft with a ban on purchase operation if he was not compensated in return.

"Special services tapped Ulyukaev's telephone conversations since the summer. In his conversation with Rosneft representatives about the privatization of Bashneft, threats were heard," the source said.

Kremlin spokesman Dmitri Peskov reacted to the news saying that "the accusations against the minister are very serious and must be backed up with solid evidence."

When the Russian government proposed privatizing 50 percent of the shares of oil company Bashneft, Ulyukaev initially said the purchase of the company by another state-run oil company seemed incoherent because of the public ownership of both.

But last September, the head of economy said the operation in which Rosneft was interested was legally possible since the law on privatization did not specifically prohibit it.

Finally, last October, the company headed by Igor Sechin, who is considered a close ally of Russian President Vladimir Putin, bought 50 percent of Bashneft's shares for 329.7 billion rubles ($5 billion.)