The CEO of Russian giant Rosneft, Igor Sechin, was added by the U.S. to its Ukraine-related sanctions list on Monday, the U.S. Treasury Department’s website said.
Sechin is the most senior energy executive to be targeted by U.S. sanctions so far.
He’s a well known ally of Vladimir Putin.
Rosneft is Russia’s biggest crude oil producer.
BP owns about 20% of Rosneft.
The sanctions did not name Rosneft itself.
Rosneft’s $55 billion acquisition of rival TNK-BP in 2013 secured its place as the largest publically traded oil and gas company in the world.
In January, Rosneft announced plans to acquire Morgan Stanley’s unit for storing, trading and transporting oil products. The deal still requires approval from the U.S. Senate Foreign Investment Committee.
Rosneft and ExxonMobil formed a joint venture in December for a pilot project to develop tight (shale) oil reserves in Western Siberia.
Rosneft holds 51%, ExxonMobil 49%.
ExxonMobil has said will bring up to $300 million in financing to the venture through 2015.