US Democratic nominee Hillary Clinton has a five point lead over Republican rival Donald Trump, according to a new Reuters/Ipsos poll released on Friday.

The poll conducted between 22-25 August saw 41% of likely voters favour Clinton with 36% selecting Trump. Clinton's lead is down from a high of twelve points earlier this month.

Some 23% would not pick either candidate and answered "refused," "other" or "wouldn't vote."

Clinton's support has fluctuated over the last number of weeks hitting a high of 45% earlier this week.

In a separate poll which included smaller parties, Clinton's support is at 39%, Trump is at 36% with Libertarian candidate Gary Johnson at 7% and Green Party nominee Jill Stein at 3%.

Both polls were conducted online in English in all 50 states and included 1,154 likely voters. The polls have a credibility interval of 3 percentage points.