Democratic Party heavyweights are accusing the FBI of involvement in a conspiracy to tarnish Hillary Clinton just days out from the United States election.

On Saturday, FBI Director James Comey announced the bureau was re-opening an investigation into Mrs Clinton’s emails following a previous probe into the former secretary of state’s use of a private mail server.

No information was disclosed about the nature of the emails or if they were sent or received by Mrs Clinton.

The emails were reportedly found during a separate FBI investigation into Anthony Weiner, the disgraced husband of Mrs Clinton’s close aide Huma Abedin.

On Monday, the FBI obtained a warrant to search Mr Weiner and Ms Abedin’s laptops, but not before Democratic leader in the Senate Harry Reid blasted the FBI.

“Your actions in recent months have demonstrated a disturbing double standard … with what appears to be a clear intent to aid one political part over another,” Mr Reid wrote to Mr Comey.

“These actions may violate the Hatch Act, which bars FBI officials from using their official authority to influence an elections. Through your partisan actions, you may have broken the law.”

Mr Reid urged Mr Comey to release compromising information the FBI allegedly has regarding Mrs Clinton’s opponent Donald Trump.

“You possess explosive information about close ties and coordination between Donald Trump, his top advisors, and the Russian government,” he said.

“I wrote to you months ago calling for this information to be released.”

However the White House has now moved to dispel accusations of political bias within the FBI, saying Mr Comey is not trying to influence the vote.

White House spokesman Josh Earnest says President Barack Obama believes Mr Comey is a man of integrity.

Mr Earnest says he has no “independent knowledge” of how Mr Comey had arrived at his decision to make public the FBI email investigation or “what factors were considered” in his decision to discuss the issue publicly.

WATCH LIVE: Josh Earnest says White House won't "criticize nor defend" FBI reopening email investigation https://t.co/H9n7JKbYS7 pic.twitter.com/E4lVMcvhz7

— CBS News (@CBSNews) October 31, 2016

Mrs Clinton spoke with a defiant tone at a campaign event on Monday, vowing not to be “knocked off course”.

“I’m not stopping now, we’re just getting warmed up,” she said. “We’re not going to be distracted, no matter what our opponents throw at us.”

Harry Reid sent a scathing letter to James Comey, slamming the timing of the new probe. Photo: AAP

On Sunday, despite the FBI’s original investigation clearing Mrs Clinton of criminal misconduct, Mr Trump seized on the probe being reopened.

“As you’ve heard, it was just announced on Friday that the FBI is reopening their investigation into the criminal and illegal conduct of Hillary Clinton – [she] has nobody but herself to blame for her mounting legal problems. Her criminal action was wilful, deliberate, intentional and purposeful.”

‘Email’ a dirty word this campaign

Emails have plagued Mrs Clinton’s campaign. Throughout her run for the White House she has been haunted by an FBI investigation into her use of a private email server.

Meanwhile, Wikileaks continues to release emails from Mrs Clinton’s campaign containing secrets like how the Democratic Party worked to favour her over fellow nominee Bernie Sanders.

Donald Trump and Hillary Clinton in one of their more civilised moments. Photo: AAP

University of Melbourne US election watcher James Cahill said the scandal wasn’t ideal for winning undecided voters.

“They’re such low information voters,” Mr Cahill said. “So sure, it’s not great that an undecided voter might glance at a headline and see ‘Clinton’, ‘email’ and ‘investigation’, those aren’t three words you want strung across a headline.”

However, he said emails hadn’t fatally hurt Mrs Clinton yet, so why would they now?

“Think how long this race has been going on, with emails an issue for Clinton the whole time,” Mr Cahill said.

“An email headline even to a casual observer of the news has been around. We’re not getting words like ‘subpoena’, ‘indictment’ or ‘charges’. These are the words that could turn things.”