Image copyright Reuters Image caption An operative employed by Republican candidate Mark Harris is accused of tampering with absentee ballots

North Carolina will hold a new election for a congressional seat following an investigation into alleged ballot-tampering for a Republican candidate.

A consultant for Mark Harris' campaign is accused of illegally posting absentee ballots during November's mid-term election campaign.

Mr Harris, who initially claimed victory over Democrat Dan McCready, has now bowed to calls for a new election.

But he maintains he was unaware of any alleged fraud in his campaign.

The three Democrats and two Republicans on the North Carolina Board of Elections ruled unanimously for a new vote on Thursday, wrapping up a week of hearings.

Political consultant Leslie McCrae Dowless allegedly manipulated the election in Mr Harris' favour by illegally collecting, falsely witnessing and otherwise tampering with absentee ballots.

On Thursday, Mr Harris took the stand and said: "The public's confidence in the ninth district seat general election has been undermined to an extent that a new election is warranted."

He also acknowledged that due to recent strokes and illness, his prior testimony before the board had included "incorrect" recollections.

Officials did not give a date for the new election, and the state's ninth district will continue to remain without representation in Washington as the new vote is organised.

The Republican initially claimed victory after edging out Mr McCready by 905 votes, out of 282,717 ballots cast.

Mr Harris said Mr Dowless had assured him his staff only helped voters obtain absentee ballots and did not do anything illegal.

Mr Harris, a Baptist pastor, recalled Mr Dowless telling him: "I don't care if it's a 95-year-old woman in a wheelchair, we do not take the ballots."

Image copyright The Washington Post via Getty Images Image caption Leslie McCrae Dowless is at the centre of the ballot-tampering controversy

The Republican candidate also referred to dramatic testimony a day earlier by his son, which left both men in tears.

Mr Harris told the court his son was "a little judgmental and has a little taste of arrogance and some other things", but that he was "very proud of him".

On Wednesday, John Harris told the elections board he had repeatedly warned his father about the "shady" tactics of Mr Dowless.

"I thought what he was doing was illegal, and I was right," John Harris testified, weeping, as his father also began to cry.

"I had no reason to believe that my father actually knew," the son added.

Mr Dowless has refused to testify.

But his former workers have testified that Mr Dowless instructed them to "pre-fill" ballot request forms, get them signed by voters, then mail in the absentee ballots.

Bladen County, where Mr Dowless operated, was the only county for which Mr Harris won the mail-in absentee ballot vote.

Prosecutors are reportedly considering whether to bring criminal charges against Mr Dowless, the New York Times reported.