Friday's report, prompted by Trump's false claims of widespread electoral fraud, found that Biden, a Democrat, won Maricopa County despite Trump's claims otherwise. The analysis recorded 99 additional votes for Biden and 261 fewer votes for Trump.

Having won Arizona and beaten Trump nationwide, Biden became president on January 20, but Trump's baseless claims persist.

In Texas on Thursday, the secretary of state's office said the state had begun an audit of the presidential election in its four largest counties - Dallas, Harris, Tarrant and Collin. Although Trump carried the state, Biden won three of those counties under review.

Hours before the announcement Trump publicly called on Republican Governor Greg Abbott of Texas to launch an audit.

Harris County's elections administrator, Isabel Longoria, said in a statement that the audit was an attempt "to delegitimise the 2020 election."

In Arizona, Biden won by just over 10,000 votes, a narrow win confirmed by a hand recount and multiple post-election tests for accuracy. Biden carried Maricopa, which includes Phoenix, by about 45,000 votes, making it critical to his defeat of Trump.

The report "confirms the county's canvass of the 2020 General Election was accurate," Maricopa County said on Twitter, adding that the review was "littered with errors and faulty conclusions".

The conclusion, if confirmed in an official announcement scheduled for later on Friday, will disappoint supporters of Trump who had pushed for the review, many in the expectation that it would prove his claims that he was robbed of victory due to widespread fraud.

Trump allies had viewed the election review in Arizona as a model for similar investigations in Pennsylvania, Michigan and other battleground states that Trump lost. Trump himself had predicted the audit would provide the evidence to support his fraud claims. So far no such proof has been produced either by Trump or his backers.

A wide array of election experts, Democrats and some Republican officials had rejected the Arizona audit as a highly partisan boondoggle run by contractors without relevant expertise and people who were out to prove that Trump won, regardless of the facts.

The lead contractor is an obscure firm, Cyber Ninjas, whose chief executive has promoted conspiracy theories about orchestrated fraud in the election.

The audit has been marked by practices that critics have described as ranging from inappropriate to bizarre, including counters marking ballots with blue ink, which can alter how they are read by machines, and workers checking for traces of bamboo fibres based on a conspiracy theory that forged ballots may have been shipped in from Asia.

In a statement, Trump claimed the review confirmed that fraud had occurred and suggested the official announcement later on Friday would be "far different" from news reports on the draft document.

Australian Associated Press