CNN has reported that U.S. investigators believe Russian hackers planted a false news story that was a factor in the decisions by several Arab countries to sever ties with Qatar.
The Kremlin contended that the CNN report was "a lie."
The CNN report late on June 6 cited unidentified U.S. officials it said had been briefed on a probe by investigators sent to Qatar to help its government look into a hacking incident that produced the fake story.
Saudi Arabia and a handful of other Sunni-ruled states have cut ties with Qatar since June 5, saying its policies have supported the funding of terrorism as well as "extremist" organizations and Iranian-backed Shi'ite rebel groups.
According to CNN, Qatar's government says the May 23 report issued by the state news agency attributed false remarks to Qatar's ruler that appeared friendly to Iran and Israel.
CNN quoted U.S. officials as saying that intelligence gathered by U.S. security agencies indicated that Russian hackers were behind the intrusion.
The CNN report said it was not clear whether the hackers suspected in the Qatar incident were linked to Russian organizations such as the GRU military intelligence agency, which has been accused of being behind cyberattacks aimed at influencing the U.S. presidential election last year.
But the network quoted U.S. officials as saying the hackers' goal appeared to be to cause rifts among the United States and its allies.
Russia dismissed the CNN report, saying there was "no evidence" of Russian involvement.
"I will say immediately that this is the latest fake, the latest lie," President Vladimir Putin's spokesman, Dmitry Peskov, said.
"We're getting tired of reacting to unsubstantiated banalities," the Interfax news agency quoted Andrei Krutskikh, a Kremlin adviser on cybersecurity, as saying. "Whatever happens it is hackers. It's a stale claim and as ever there is zero evidence, and conclusions are drawn before the incident is even investigated."
U.S. President Donald Trump sent mixed messages on the issue on June 6. He initially appeared to hail the move by Saudi Arabia and other Arab states, saying that the moves targeting Qatar showed his advice on a visit to Riyadh last month was "already paying off" as the Arab states were taking a "hard line" against the financing of terrorism.
The White House seemed to take a different tone after Trump spoke by telephone with Saudi Arabia's ruler, King Salman. A White House statement said that Trump underscored that "a united Gulf Cooperation Council" -- a regional group that includes Qatar -- is "critical to defeating terrorism and promoting regional stability."
With reporting by CNN and AFP