The US elections set to be held in November this year may become the “most rigged” in US history, US President Donald Trump tweeted.

"Because of MAIL-IN BALLOTS, 2020 will be the most RIGGED Election in our nations history - unless this stupidity is ended. We voted during World War One & World War Two with no problem, but now they are using Covid in order to cheat by using Mail-Ins!" Trump tweeted.

Earlier Monday, Trump said millions of postal ballot papers in US elections would be printed overseas. Trump has repeatedly spoken out against the option of holding a vote by mail, which may be allowed in several states amid the pandemic.