The United States has raised concerns about the arrest of Russian oil tycoon Mikhail Khodorkovsky. US ambassador in Moscow, Alexander Vershbow said the arrest could raise doubts for foreign investors. Vershbow told Interfax news agency "recent events provoked questions about whether or not Russian legislation is being applied selectively". Khordorkvsky, head of oil firm Yukos was charged with offences including defrauding the state out of USD 1 B. Vershbow told the Russian news agency that Washington "was concerned about the escalation of tensions surrounding the Yukos company". "I think that following these events foreign companies operating on the Russian market and prospective investors are going to have new doubts," he said.