The United States has imposed additional sanctions on Russia for attacking a former Russian spy and his daughter in the UK in 2018 with a "novice" nerve gas.

State Department spokeswoman Morgan Ortagus explained the decision by saying: “This act has endangered thousands of lives.

The sanctions, effective later this month and for a year, will expel Russia from US banking services, including debt financing, and prevent the Vladimir Putin government from buying US products for use in its chemical and biological weapons program.

And Russian Foreign Ministry spokeswoman Maria Zaharova said the second round of US sanctions imposed on Russia over the Skripalj case shows that the investigation was rigged.

"This is another huge and strong proof that the story with Skripalj was fabricated, that it was a provocation," she told a television interview on Rosia1, adding that the story, presented by Theresa May's government as the official version, had discredited herself, reports TAS S.

Trump issued an executive order late Thursday imposing another round of sanctions on Moscow, which denied any wrongdoing in the Skripalj case.

The US has already imposed sanctions on Russia in 2018 for using chemical weapons and thus violating international law.

Former double-spy Sergei Skripalj and his daughter Julia were found poisoned in Salisbury on March 4, 2018, and a toxic chemical was on the door handle.

They were in critical condition at the hospital for weeks. London accused Moscow of being behind the poisoning, alleging that a novice was used in the attack.

Moscow has denied the UK's allegations, saying that a program aimed at developing such a substance did not exist in either the Soviet Union or Russia.

The British military chemical laboratory in Porton Down has failed to determine the origin of the substance that poisoned the Skripalev, a Russian agency has reported.