THE UK Labour leadership contest was engulfed in a dirty tricks row yesterday, after one of the candidates was forced to deny sleeping with her campaign manager.

Liz Kendall accused rivals of conducting a smear campaign, after unfounded claims were circulated that she was in a relationship with recently divorced MP John Woodcock.

Speaking with Kendall’s approval, Woodcock said the “systematic” campaign was “totally unacceptable” and the rumour was “not true, has never been true and would never be true”.

In another blow to the party’s reputation, it was reported that up to 1000 people who signed up to vote on the leadership had been barred for belonging to or supporting other parties.

Around 140,000 new recruits have signed up since May, prompting fears of entryism from both the left and the right. The belief is that the left wish to boost support for the left-wing frontrunner Jeremy Corbyn, while Tory supporters have secretly signed up to back Corbyn in the hope he will make Labour unelectable and split the party.

Deputy leadership candidate Stella Creasy yesterday admitted Labour had “missed a trick” by not learning from the experience of American primary elections, where voters register as supporters of particular party.

Against the backdrop of infighting and administrative chaos, Corbyn made clear that to him the contest was about hope and a new mood in the party.

“We are not doing celebrity, personality, abusive politics – we are doing ideas,” he said.

He downplayed claims of entryism and Tory troublemakers, saying: “The numbers don’t stack up. The entryism, if anything, is of enthusiastic young people. We can all be happy about that.”

Woodcock told reporters the smears about him and Kendall started a month ago, and the pair decided to confront them publicly after two journalists told them the claims came from the campaign of one of Kendall's rivals.

The rumours included the suggestion that Kendall, who recently separated from the comedian Greg Davies, had holidayed with Woodcock and his young children in France.

"People who are spreading these rumours about Liz and me need to remember how much damage these acts of smear can do," Woodcock said.

"This is clearly being done systematically, to damage Liz's campaign. It is totally unacceptable and that is why I have decided to talk about this publicly.

"It is hurtful for my family, and it is designed to make things difficult for Liz."

The most Blairite of the four leadership hopefuls, Kendall is now seen as the rank outsider in a contest dominated by ‘Corbynmania’, but when the rumours began she was viewed as a more credible threat to her rivals, who include Andy Burnham and Yvette Cooper.

The 44-year-old previously complained of a “sexist” jibe by a female Labour MP who said Cooper would be preferable as she was a mother - Kendall does not have children.

Woodcock, the MP for Barrow and Furness, said the latest rumours “must stop now” and threatened to expose those responsible after the contest ends on September 12.

“This has given me a small insight into the kind of difficulty so many women come across, when it is said that they are only where they are because they are sleeping with someone or someone fancies them,” he said.

Meanwhile, Corbyn said yesterday his unexpectedly successful campaign had tapped into the same anti-austerity mood behind Syriza in Greece and Podemos in Spain.

“The mood is there and we happen to be in the middle of it. It is not just here. There are equivalent movements across Europe, the USA and elsewhere. It’s been bubbling for a long time. It is opposition to economic orthodoxy that leads us into austerity and cuts. But it is also a thirst for something more communal, more participative. That, to me, is what is interesting in this process.”

Despite frequently being compared to former Labour leader Michael Foot, Corbyn said his favourite party leader was actually the Scottish QC John Smith, who died aged 55 in 1994.

“What a decent, nice, inclusive leader he was. What a tragedy he died when he did.”

In other developments in the UK Labour leadership race, Cooper accused David Cameron of “vandalising democracy” with his plan to appoint a raft of new Tory peers to the House of Lords without wider constitutional reform.

[BLOB] In the Scottish leadership contest, frontrunner Kezia Dugdale said that if she won next Saturday, Labour would pay more to teachers who work in deprived areas.

Underdog Ken Macintosh said most Scottish Labour members remained undecided about who they would elect and said he was “confident” of victory, claiming momentum was with him.

An SNP spokesman said: "North and south of the border, Labour is riddled with back-biting and double crossing; it has totally lost touch with the people and is in terminal decline."

Scottish Tory deputy leader Jackson Carlaw said: “As every day passes it's becoming clearer that the Labour party are in total disarray.

"Voters in Scotland will now realise that the Scottish Conservatives are the only serious pro-Union party to vote for a next year's Holyrood elections."