Keir Starmer‘s leadership campaign has urged Labour bosses to intervene over ”unfair” allegations of a data breach by members of his team.

The race to succeed Jeremy Corbyn descended into acrimony after Labour informed the data watchdog of allegations that Sir Keir’s team had breached strict rules by hacking into the party’s membership database.

Ex-Labour MP Jenny Chapman, the chair of Sir Keir’s campaign, said the accusations were “utter nonsense” and called on Labour’s general secretary, Jennie Formby, to withdraw the complaint.

The allegations emerged as Labour investigated a separate complaint into claims that rival candidate Rebecca Long-Bailey had shared links to a Labour phone-banking system called Dialogue with volunteers, which could have given them access to more than half a million party members.

Her team insist they have done nothing wrong and it is understood that party officials have not found any evidence to substantiate the claims.

But Labour has now reported Sir Keir’s team to the Information Commissioner’s Office (ICO) for an alleged breach, which sources say occurred checking out the allegation that Ms Long-Bailey may have broken the rules.

Ms Chapman, a former shadow Brexit minister, told BBC Politics Live: ”This is utter nonsense, this is something Labour Party members will be just having their heads in their hands over. This is not what we want to see.

“They need to withdraw that allegation because its so serious and it is affecting those two individuals, who have been named publicly.

“I think they need to withdraw that because there is no evidence to support that allegation because it just simply didn’t happen.”

Asked whether Ms Formby should intervene, she said: “That allegation needs to be withdrawn because it is unfair to make an allegation as serious as that.

“Whether or not there is a campaign going on isn’t the point.”

The battle to replace Jeremy Corbyn as Labour leader Show all 8 1 /8 The battle to replace Jeremy Corbyn as Labour leader The battle to replace Jeremy Corbyn as Labour leader Keir Starmer The former director of public prosecutions undoubtedly has announced that he is standing for the leadership. He is highly-regarded by both left-wingers and centrists in the party. As Labour’s shadow Brexit secretary, he played a key role in the party’s eventual backing of a second referendum. Before becoming an MP, he was a human rights lawyer - conducting cases in international courts including the European Court of Human Rights. Launching his bid, Starmer said that Labour must listen to the public on how to change "restore trust in our party as a force for good." A YouGov poll places him comfortably in the lead as the preferred candidate of 36% of party members EPA The battle to replace Jeremy Corbyn as Labour leader Lisa Nandy Wigan MP Lisa Nandy has announced she wil stand for the leadership. In a letter to the Wigan Post she said she wanted to bring Labour "home" to voters in its traditional strongholds who have abandoned the party. Nandy went on to say that she understands "that we have one chance to win back the trust of people in Wigan, Workington and Wrexham." A YouGov poll shows that Nandy is the first preference for 6% of partymembers. Getty The battle to replace Jeremy Corbyn as Labour leader Rebecca Long Bailey A key ally of the current left-wing leadership of the party, the Salford & Eccles MP is viewed in some quarters as the natural successor to Mr Corbyn and describes herself as a “proud socialist”. Highly regarded by the shadow chancellor, John McDonnell. She won also won plaudits for her performance filling in for Corbyn both at prime minister’s questions and during the general election debates. The shadow business secretary grew up by Old Trafford football ground and began her working life serving at the counter of a pawn shop. Launching her leadership bid, Long Bailey said the party needs to make the positive case for immigration as a "positive force." She also broke with Corbyn over Trident, saying "If you have a deterrent you have to be prepared to use it." PA The battle to replace Jeremy Corbyn as Labour leader Angela Rayner - Deputy leadership Shadow education secretary Angela Rayner has joined the contest for deputy leadership of the party. After ruling herself out of running for the leadership, the Ashton-under-Lynne MP launched her bid for deputy warning that Labour faces the "biggest challenge" in its history and must "win or die." She is close with leadership contender Rebecca Long Bailey PA The battle to replace Jeremy Corbyn as Labour leader Rosena Allin-Khan - Deputy leadership Shadow sport minister Rosena Allin-Khan said Labour need to listen with "humility" to lost voters as she launched her bid for the deputy leadership. Writing in The Independent, the MP for Tooting refelcted: "We shouldn’t have ignored the warning signs in Scotland, and now we’ve paid the price in northern England, across the midlands and in Wales." PA The battle to replace Jeremy Corbyn as Labour leader Dawn Butler - Deputy leadership Shadow women and equalities secretary Dawn Butler was first to announce her bid for the deputy leadership. The Brent Central MP has served in Jeremy Corbyn's shadow cabinet since 2016 PA The battle to replace Jeremy Corbyn as Labour leader Ian Murray - Deputy leadership Labour's only MP in Scotland said that the architects of the party's "catastrophic failure" in the December election can not be allowed to lead the party forward PA The battle to replace Jeremy Corbyn as Labour leader Richard Burgon - Deputy leadership Shadow justice secretary Richard Burgon is standing as a continuity candidate, flaunting his loyalty to Jeremy Corbyn and saying it is wrong to blame the current leader for the election defeat PA

Sir Keir took an early lead in the leadership race by scooping support from key trade unions and local parties but he faces a challenge from Ms Long-Bailey, who is regarded as the left-wing successor to Mr Corbyn.

Wigan MP Lisa Nandy is also on the ballot paper, while Emily Thornberry, the shadow foreign secretary, is struggling to win sufficient support from affiliated groups.

Leadership candidates are not supposed to have access to Labour’s 500,000-plus membership lists until the nominations window closes on 14 February.

A spokesperson for Ms Long-Bailey’s campaign said: “The investigation into Keir Starmer’s campaign over an alleged data breach should not be allowed to distract from a moment of significant importance in determining the future direction of our party.

“As Rebecca’s campaign has said previously, the accessibility of members’ data stemmed from a failure to close Dialogue at the end of the general election campaign.”

Ms Formby has written to all candidates following the reports about alleged misuse of membership data and party systems.

A Labour spokesperson said: “The Labour party takes its legal responsibilities for data protection, and the security and integrity of its data and systems, extremely seriously.

“We have written to all leadership candidates to remind them of their obligations under the law and to seek assurances that membership data will not be misused.”