US justice chief authorises investigation into voting irregularities

US Attorney General Bill Barr has given federal prosecutors blanket authorisation to open a probe into voting irregularities, as President Donald Trump claimed that he lost the presidential election due to fraud.

The order came as Trump battles to reverse Democratic rival Joe Biden's narrow wins in several key states -- Pennsylvania, Nevada, Georgia, and Arizona  -- that give the latter enough electoral votes to win the overall presidential election.

Barr has long been a close defender of Trump. He stressed his letter to US attorneys around the country was not an indication that the Justice Department had evidence yet of genuine cases.

"Given that voting in our current elections has now concluded, I authorise you to pursue substantial allegations of voting and vote tabulation irregularities prior to the certification of elections in your jurisdictions in certain cases," Barr said in the letter to the attorneys.

He added, "Such inquiries and reviews may be conducted if there are clear and apparently-credible allegations of irregularities that, if true, could potentially impact the outcome of a federal election in an individual state."

Voting fraud investigations are normally the purview of individual states, which establish and police their own election rules. Justice Department policy has been to hold back any federal involvement until vote tallies are certified, recounts completed and races concluded.

Barr, however, told the attorneys that "practice has never been a hard and fast rule," and stressed that, if they see anything that could reverse the results of last Tuesday's election, they should pursue it.

The Trump campaign and the Republican party have filed or threatened legal actions in several of the states hoping to change the outcome with ballot disqualifications and recounts. But so far their actions have gone nowhere, and state officials have challenged them to provide proof of allegations. 

Trump had reportedly pressured Barr to get involved on his behalf even weeks before the election.