MOSCOW: Russia on Tuesday criticised Washington's blacklisting of a high-ranking official and the suspects in the murder of ex-spy Alexander Litvinenko as a move by the outgoing administration to further sour ties.

Kremlin spokesman Dmitry Peskov told reporters the US decision to blacklist Investigative Committee chief Alexander Bastrykin and Litvinenko's alleged assassins, lawmaker Andrei Lugovoi and Dmitri Kovtun, represented "further steps in the artificially created degradation of our relations".

"We deeply regret the fact that a lingering period of unprecedented degradation in our bilateral ties occurred during (US President Barack) Obama's second presidential term," Peskov said.

"We are convinced that this does not coincide with our interests or those of Washington."

The US Treasury on Monday added Bastrykin, Lugovoi and Kovtun to the Magnitsky Act sanctions list in the latest spike of diplomatic tensions between Moscow and Washington.

State Department spokesman John Kirby said the additions followed "extensive research" and targeted individuals with "roles in the repressive machinery of Russia's law enforcement systems, as well as individuals involved in notorious human rights violations."

Relations between the two countries, already badly damaged by the conflicts in Ukraine and Syria, have tumbled further still as Washington has accused the Kremlin of orchestrating cyber attacks aimed at influencing the results of November's White House race.

US intelligence agencies last week released a report saying that Russian President Vladimir Putin personally ordered a hacking campaign and media manipulation to upend Democratic candidate Hillary Clinton's efforts to win the election.

Moscow, which branded the report baseless and amateurish, has repeatedly rejected the accusations, over which Obama last month expelled 35 Russian diplomats allegedly involved in espionage and due to "harassment" of US diplomats in Russia.

Deputy Russian Foreign Minister Sergei Ryabkov said in a statement the Obama administration's efforts to sanction Moscow before relinquishing power were "disgraceful".

"Its bad manners and outright Russophobia these days have mixed with its anger over the loss of its candidate in the presidential elections and its urge to search for those guilty for the defeat everywhere but at home," Ryabkov said.

- 'Absurd' sanctions -

Lawmaker Lugovoi dismissed his inclusion on the sanctions list as "absurd", telling Russian media he was "perplexed" by the decision.

"I think that Obama is now rushing before handing over ... to harm and spite Russia in any way he can, and this has led to absurd things," RIA Novosti state news agency quoted him as saying.

Litvinenko, an ex-spy turned Kremlin critic, died of radiation poisoning in 2006 aged 43, three weeks after drinking tea laced with radioactive polonium at an upmarket London hotel.

An inquiry last year found that Lugovoi and Kovtun were likely to have carried out Litvinenko's poisoning on the instructions of the Russian security services -- accusations Lugovoi has dismissed as "nonsense".

The Magnitsky Act was originally passed to allow US officials to impose sanctions on Russians implicated in the 2009 prison death of Russian tax fraud whistleblower Sergei Magnitsky.

But more individuals have been blacklisted over the years.

The list now includes 44 people whose assets are frozen under US jurisdiction, and who are barred from doing business with Americans or receiving US visas.