The US has identified the Russian agents behind alleged hacking ahead of the presidential election won by Donald Trump in November, reports say.
The agents, whose names have not been released, are alleged to have sent stolen Democratic emails to WikiLeaks to try to swing the vote for Mr Trump.
Russia denies any involvement and WikiLeaks founder Julian Assange says Moscow was not the source.
Intelligence officials are due to brief Mr Trump, who doubts the claims, later.
At about the same time, President-elect Trump appeared to question the intelligence agencies’ findings in a tweet, asking why they decided not to request to examine computers belonging to the Democratic National Committee (DNC).
Mr Biden said he had read a US intelligence report outlining Russian involvement, the details of which are emerging in US media.
According to CNN, the Washington Post and NBC News citing intelligence sources, agencies had intercepted communications in the aftermath of the election showing senior Russian government officials celebrating Donald Trump’s win over rival Hillary Clinton.