Russia's Economy Minister Alexei Ulyukayev has been charged with taking a bribe to endorse a state takeover.
Investigators said he received a $2m (£1.6m) payment. The minister pleaded not guilty to the charge.
Mr Ulyukayev is the highest-ranking Russian official held since the 1991 coup attempt in what was then the USSR.
The investigators said he had "threatened" to create obstacles for Rosneft when it took a 50% stake in another state oil company, Bashneft.
The minister called his arrest was "an act of provocation against a state official", his lawyer said. A court has placed him under house arrest until 15 January.
President Vladimir Putin later dismissed Mr Ulyukayev, 60, because of "the loss of trust" in him. Mr Ulyukayev's deputy Yevgeny Yelin was appointed as acting economy minister.
An economic liberal in the 1990s, Mr Ulyukayev became deputy chairman of Russia's central bank in 2004. He was appointed economy minister in 2013.
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