State Duma speaker Vyacheslav Volodin said foreign operators such as German intelligence agents may have poisoned the Kremlin critic.
The suspected poisoning on the Russian opposition figure bears the hallmarks of the 2018 attack on Sergei Skripal and his daughter Yulia, and a Bulgarian arms maker, Der Spiegel reported.
A Moscow State University professor announced plans to include the two men accused of poisoning a Russian double agent in the U.K. in a conference on information warfare.
The State Department is not saying when it will implement the sanctions, noting that there is no deadline in the law for imposing them.
Two Russian men identifying themselves as the suspects in the poisoning of an ex-Soviet agent in the English countryside said they were just sightseeing.
In the wake of the nerve agent attack in Salisbury, England, an intelligence chief pledged to fight back.
Moscow has cast doubt over the relevance of the footage showing two Russian nationals visit the U.K., travel to Salisbury and leave during the attack.
The U.K. cannot seek an extradition from Russia, but a European arrest warrant has been issued.
Earlier in the week, reports claimed U.S. officials had sought to establish dialogue with Moscow ahead of the State Department's new sanctions.
Prosecutors in the U.K. are prepared to file an extradition request for two Russians they suspect carried out a nerve agent attack that killed one person and injured three others.
Police are combing thousands of hours of closed-circuit TV footage.
The Russian government previously accused British intelligence officials of carrying out the Skripal poisoning as a way to stir up anti-Moscow sentiment.
Reports suggest the 44-year-old and her partner handled a contaminated item.
The man and woman who fell ill in Amesbury were exposed to the same nerve agent that hospitalized a former Russian agent and his daughter.
The suspected poisoning incident occurred a few miles away from where former Russian spy Sergei Skripal and his daughter were attacked with a nerve agent.
The ex-Russian spy and his daughter were hit with an attack that used 50-100 grams of Novichok, the head of the OPCW has said.
Vladimir Uglev identified the poison that hospitalized former double agent Sergei Skripal as Novichok.
Chapman was part of a spy swap deal with the U.S. which saw Sergei Skripal handed over.
The man who may have invented the poison that took down Sergey Skripal has said he supports the British government's stance on Russia.
Sergei Skripal is "improving rapidly," while his daughter can now look forward to leaving hospital.
Meanwhile, Russia's foreign minister accused the U.K. of arm-twisting other countries to "demonize Russia."
Russia's top diplomat argued that U.S. military presence in Syria was illegal and rebutted accusations over the poisoning of an ex-Soviet spy.