Labour’s Chris Williamson has said that Ian Austin, who left the party on Friday, “is no loss to the Labour party”.
Mr Austin was the ninth Labour MP in a week to quit Jeremy Corbyn's party, claiming there was a "culture of extremism, antisemitism and intolerance".
The MP for Derby North told talkRADIO’s Dan Wootton: “The fact is that Ian Austin is no loss to the Labour party. He has been behaving as a fifth columnist ever since Jeremy Corbyn was elected as Labour leader – ever since the huge surge of membership in the Labour party.
“Let’s be honest he fought the last election of false pretences. He did not support the programme that Labour put forward and that is what actually carried him into office again.
“He got elected because he was a Labour candidate and he got elected on the hard-work of Labour party activists who he is incredibly discourteous about.”
Mr Williamson also accused the MP for Dudley North of “embarrassing outbursts”.
He added: “He has clearly lost the plot in my opinion and he has never really come to terms with the fact that the Labour party is now a mass party with a policy programme that is overwhelming supported by the British people.
“If he was a genuine Labour supporter, he would have actually knuckled down and fought for the programme that Labour is trying to implement.”
When Dan Wootton asked Mr Williamson to address that the Labour party has a problem with anti-semitism, the MP accused him of a “grotesque slur”.
“The Labour party has done more than any other political party in this country to address the issue of anti-semitism,” Mr Williamson said.
“The Labour party has a proud record of fighting all forms of racism ever since we were founded.
“We are the Labour party that stood shoulder-to-shoulder with the Jewish community in Cable Street against Oswald Mosley’s fascists.”