Iran is targeting African-American voters and Muslims in the critical state of Michigan in an attempt to sway the US election against Donald Trump, according to a new report.

Iran is ramping up efforts to interfere with the US election with fake "news" websites and hackers targeting Donald Trump, American officials and researchers say, as the Republican nominee reported threats on his life from the Islamic republic.

Federal prosecutors in the United States have today filed criminal charges in the case. The hackers had allegedly targeted members of former president Donald Trump's campaign.