The latest polls in the US election show Hillary Clinton is bouncing back after a dip in numbers following the FBI's announcement it would be reopening its investigation into her emails.

With just four days to go until the 8 November election, the Democrat has edged out over her GOP rival Donald Trump, also leading in nine of 11 key battleground states.

Two national polls show Clinton leading; a head to head poll from ABC/ Washington Post Tracking showing her three points up on Trump, with 49 points to his 46, and the same poll from IBD/TIPP Tracking putting her a point ahead of the Republican.

A national four-way poll also from ABC/Washington Post Tracking, including Gary Johnson and Jill Stein, has Clinton leading on 47, Trump on 44, Johnson with 3 and Stein with 2 points, according to Real Clear Politics.

However, Trump is leading in two of the three largest swing states, Florida and Ohio, which carry a combined 47 Electoral College votes. A poll from LA Times/USC Tracking also shows the GOP nominee leading by four points, on 47 to Clinton's 43 points, according to Real Clear Politics.

In the final countdown to what has been a roller coaster presidential race, the two candidates are scrabbling to pick up votes in key battleground states and campaigning in newly viable states including Arizona, where Clinton is fighting for a win in a state that has voted Republican for the past 20 years.

Both candidates have seen the past month of their campaigns hit by scandal, with Trump facing a backlash after footage was released of him making lewd comments about women, and following allegations of abuse from several women, which he has denied.

Clinton meanwhile, has seen the FBI re-launch its investigation into her use of a private email server during her time as secretary of state, in a decision her campaign team has questioned due to its timing so close to the election.