The suspected Russian hack of the Democratic National Committee (DNC) formed part of a wave of Russian cyber attacks aimed at political organisations and academic think tanks in Washington, according to US officials briefed on the investigations.
The weekend saw Wikileaks publish hundreds of emails from the DNC. The group did not identify the source, though, the campaign of presumptive Democratic nominee Hillary Clinton blamed Russia, claiming the release of stolen emails was intended to help Republican nominee Donald Trump.
Meanwhile, the FBI had started investigations into the DNC hack and experts had met Republican National Committee, as also major campaigns, to discuss their security measures, according to the officials.
They added no fresh intrusions had so far been detected at the Republican National Convention or the campaigns of the two major party candidates.
Clinton campaign manager Robby Mook spoke to CNN's Jake Tapper on "State of the Union" yesterday, regarding the "changes to the Republican platform to make it more pro-Russian," which could provide some of the motive behind the hacks.
"I don't think it's coincidental that these emails were released on the eve of our convention here, and I think that's disturbing," he said.
Trump's son, Donald Trump Jr, denied the allegations over encouragement to Russians to hack the DNC.
Meanwhile, The Washington Post reported citing several individuals familiar with the situation that national security officials had been growing increasingly concerned about possible efforts by Russia to meddle in the election.
Last week, hours before the release of the records by the website WikiLeaks, the White House convened a high-level security meeting to discuss reports that the Democratic National Committee system had been hacked by Russia.
Although other experts remained sceptical of the Russian role, the hacking incident had caused alarm within the Clinton campaign and also in the national security arena.
Mook, told ABC News yesterday that ''experts are telling us that Russian state actors broke in to the DNC, took all these emails and now are leaking them out through these Web sites. .?.?. It's troubling that some experts are now telling us that this was done by the Russians for the purpose of helping Donald Trump.''