US election: Donald Trump encourages North Carolina voters to vote twice

President Donald Trump talks to a crowd of supporters after arriving at Wilmington International Airport. Photo / AP

US President Donald Trump has suggested during a trip to North Carolina that people should commit voter fraud to test if the mail-in voting system works.

Trump's comments to a local journalist at an airport stop in Wilmington were caught on video after the reporter informed the president that 600,000 voters in North Carolina could vote absentee.

"I don't like that," Trump said told the crowd gathered on the airport tarmac.

"So let them send it in and let them go vote, and if their system's as good as they say it is, then obviously they won't be able to vote. If it isn't tabulated, they'll be able to vote. So that's the way it is. And that's what they should do," Trump suggested to a crowd gathered at the airport in Wilmington, North Carolina, where he had travelled to pay tribute to the city's World War II history.

It is illegal to vote more than once in an election.

Trump's latest comments continue a trend of the President trying to sow confusion about the US mail-in voting process.

Democrats have been pushing for more mail-in voting options because of the ongoing coronavirus pandemic.

With the USS Battleship North Carolina in the background, President Donald Trump speaks on Wednesday. Photo / AP

The Trump campaign and the Republican National Committee have sued states that have moved to expand access to mail-in voting in response to the pandemic, including Nevada, New Jersey and Montana.

"President Trump encourages supporters to vote absentee-by-mail early, and then show up in person at the polls or the local registrar to verify that their vote has already been counted," Trump campaign official Tim Murtaugh said.

"It's amazing that the media can go from insisting that voter fraud doesn't exist to screaming about it when President Trump points out the giant holes in the Democrats' voting schemes."

North Carolina is a key swing state that helped Trump win the White House over Democrat Hillary Clinton in 2016.