WASHINGTON: The United States is expected to impose sanctions as early as this week on Russians connected to the poisoning of Kremlin critic Alexei Navalny, three sources familiar with the matter said on Monday.

The sources declined to identify the targets or the legal authorities Washington would use to penalize them as it seeks to impose consequences for the poisoning of Navalny. He fell ill on a flight in Siberia last August and was airlifted to Germany, where doctors concluded he had been poisoned with a nerve agent.

The State Department did not immediately respond to a request for comment on the possibility of sanctions.

Former U.S. President Donald Trump did nothing to punish Russia, which top U.N. human rights experts said on Monday was to blame for attempting to kill Navalny as part of a pattern of attacks on critics to quash dissent.

Many Western countries say Navalny was poisoned with a nerve agent, but the Kremlin has denied any role in his illness and has said it has seen no proof that he was poisoned.

After his treatment in Germany, Navalny, 44, returned to Russia in January. He was arrested and later sentenced to more than 2-1/2 years in jail for parole violations that he said were trumped up.

Democratic U.S. President Joe Biden last month called the jailing of Navalny 'politically motivated' and called for his release. He has pledged a new and tough approach towards Moscow, saying the United States would no longer be 'rolling over' in the face of aggressive action by Russia.

Washington and Moscow disagree on a wide range of issues on top of Navalny, such as Russia's military ambitions in Ukraine and Georgia, as well as a cyberattack on U.S. government agencies last year that Washington blames on Russia.