CNN notes the new development "reveals that Mueller's team has intensified its focus into the potential flow of money from Russian Federation into the United States election as part of its wide-ranging investigation into whether the Trump team colluded with Russia's interference in the 2016 presidential election". The move targeting Russia's business elite could affect people close to Russian President Vladimir Putin.
As it was reported earlier, the European Union has officially extended the anti-Russian sanctions imposed for Russia's annexation of Crimea.
The Trump administration used CAATSA last month to slap sanctions against two-dozen Russian individuals and entities for their involvement in a two-year campaign of cyberattacks against the U.S.
While the steps were the most significant taken against Moscow since Trump took office in January 2017, his decision at the time not to target oligarchs and government officials close to Putin drew criticism from United States lawmakers in both parties.
The measures will be taken in the framework of the Countering America's Adversaries Through Sanctions Act (CAATSA), which was drafted by Republicans and Democrats in connection with the annexation of the Crimean Peninsula, the Russian participation in the Syrian War and the intervention in the U.S. presidential elections.
Asked about the planned sanctions, Kremlin spokesman Dmitry Peskov told reporters on Thursday: "The phrase "Russian oligarchs" is considered inappropriate".
US-Russian ties have worsened with allegations, which Moscow denies, that Russia was responsible for a March 4 nerve agent attack on a former Russian spy in Britain.
None of the three Russians were identified by CNN's sources.
"The administration is committed to implementing the CAATSA law as we have said many times", a senior USA official told the outlet.