Exeter MP Ben Bradshaw has told ITV West Country that up to ten per cent of new party members in his constituency have no record of supporting the Labour Party.
He made his comments as ballot papers started arriving through the letterboxes of the 450,000 people registered to take part in the vote.
It's great we are getting all these new people joining the party and registering as supporters but we do need to check that they are genuine supporters and not supporters of other parties that are just trying to take part in the leadership election to do us damage. We found in Exeter that around ten per cent of the new registered supporters have always been people who've been very hostile to Labour - we know this from our canvassing records - and have voted for other parties.
Mr Bradshaw insisted he was prepared to work with any of the leadership candidates, including left-winger Jeremy Corbyn, the overwhelming leader in the contest.
But he backed Gordon Brown's comments at the weekend.
I thought it was an excellent speech - Gordon was making the very obvious point that principles and values are essential in politics but they are impotent if we are not prepared to and can't win elections.
Bristol MP Kerry McCarthy has backed MP Andy Burnham as the next Labour leader.
The representative for Bristol East was speaking after attending a rally hosted by the leadership candidate in the West Country this weekend.
Jeremy Corbyn the MP for Islington North is favourite for the position.
A memorial to former Labour Party leader Michael Foot has been unveiled in Plymouth.
The memorial, in Freedom Fields Park, was paid for by donations from a public appeal.
"The support the appeal has received from Plymouth businesses has been incredible and testament to how popular Michael was" said Luke Pollard, one of the organisers.
Mr Foot served as MP for the city from 1945 to 1955, before going on to win a seat in south Wales in 1960.
"Michael loves benches where he could sit down in a park and read" said appeal chairman Peter Jones.
"It's fantastic that the memorial overlooks Plymouth Sound... he felt that the sea defined the city".
A memorial to former Labour leader Michael Foot will be unveiled in Plymouth later today at 3.30pm, five years after his death.
£40,000 has been raised for a memorial granite bench which will stand in Freedom Fields.
Mr Foot who passed away in 2010, was the MP for Plymouth Devonport for many years and was born in a house which overlooked the park.
The Labour leader was also a keen Plymouth Argyle fan.
Exeter's MP Ben Bradshaw will stand for Labour deputy leadership, after getting the last of the 35 names he needed in a last-minute scramble for nominations.
Late yesterday he was still ten short of the number of backers he needed, but managed to get enough to get him over the line by today's midday deadline.
He is one of five candidates for the deputy post, and the winner will be announced in September.
Former culture secretary Ben Bradshaw has confirmed he is to stand for the deputy leadership of the Labour Party.
The Exeter MP said his "big tent" approach to politics was the only way Labour would attract the voters it needs to win the next election.
Announcing his intention to run, he told his local party: "Labour did badly everywhere and in Wales and England outside London we went backwards against the Tories."
"Labour must and could win the next election, but only if it broadens its appeal by adopting sensible, centre-left politics which celebrate wealth creation and entrepreneurship as vital means of delivering social justice."
"I know I face an uphill task getting enough nominations from fellow MPs to get on the ballot paper. That would be hard for anyone from a part of Britain with so few Labour colleagues."
"But it's exactly because I believe it is vital that we listen to and hear the voices of those members, candidates and defeated MPs from areas that are under-represented in Parliament and where we must win again that I have decided to have a go."
Other contenders tipped to join the battle to replace Harriet Harman include Tom Watson, West Bromwich East MP since 2001, who has reportedly been crowd-funding for his bid, and Walthamstow MP Stella Creasy.
With less than a week to go until the general election Harriet Harman has been campaigning in the south west.
Ian Axton asks Labour's deputy leader about her party's plans to delay the dual A358 link between the M5 and A303.
The party has made a manifesto pledge to use the money that the Conservatives would spend on the road to freeze rail fares instead.
Labour's deputy leader Harriet Harman is in the region today as the party looks to increase it's presence in the South West.
Labour currently hold two seats - Exeter and Plymouth Moorview but the party is targeting Plymouth for possible gains.
With the general election just around the corner, ITV West Country's Ian Axton quizzed Harriet Harman about when the Labour leader Ed Miliband would be visiting Devon and Cornwall.
You can watch more of the interview on tonight's show at 6pm.
Labour's deputy leader Harriet Harman is in the region today as the party looks to win seats in the south west.
The party currently holds two seats - but is targeting Plymouth for possible gains. Labour currently hold Exeter and Plymouth Moorview.
David Cameron today hit out at Labour's Ed Balls after comments he made about the letter left in the Treasury at the end of Labour's last term in office.
The Shadow Chancellor has been quoted today as saying the letter was a "joke". The Prime Minister described that as "frankly appalling".
In a recent interview with ITV West Country, presenter Ian Axton actually showed Mr Balls the letter which has been exclusively filmed by ITV News.
Watch his reaction here: