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President Donald Trump has offered a $1m (£750,000) reward to people who report cases of voter fraud in the US which lead to a conviction.

Ahead of the midterm elections on 3 November, Trump has been casting doubt on the security of the vote - alleging "rampant" cheating in postal voting and non-citizens voting.

However, studies suggest actual cases of these are extremely rare.

BBC Verify has taken a look at the evidence and Trump's proposed changes to the voting system.

How has Trump tried to change postal voting?

For years, Trump has made repeated unsubstantiated claims that postal voting leads to widespread fraud.

He has also encouraged Republicans to vote by mail in the midterms and has said he has cast his ballot by post in the past.

The president has been unsuccessful in his push for Congress to pass an act which would only allow people to vote by mail if they are disabled, ill, serving in the military, or travelling.

The majority of states allow , external people to…