Russian shares have fallen sharply after US and EU bolstered sanctions against Russia over its alleged support for separatists fighting in Ukraine.
The sanctions targeted major banks, defence firms and energy companies including Rosneft.
The RTS stock index, which is based on the share prices of 50 of Russia’s most prominent firms, fell by more than 4 per cent.
Prime Minister Dmitry Medvedev called the sanctions “evil” and said that Russia might increase defence spending.
The boosted sanctions were imposed against Rosneft and fellow energy company Novatek, plus two banks: Gazprombank, and the state-owned Vnesheconombank.
Rosneft shares fell by over 5 per cent in Thursday morning trading, and Novatek shares lost 11 percent in value.
The Moscow-based Micex stock exchange, which trades in roubles, fell by over 2.6 per cent.
BP said that sanctions appeared to restrict access to US medium and long-term debt, and to equity capital markets, for the firms being sanctioned.
The energy giant, which owns around a 20 per cent stake in Rosneft, gets about a quarter of its oil from Russia.
BP shares fell over 1.5 per cent on yesterday morning.