Labour’s deputy leader has called on Jeremy Corbyn to withdraw the whip from Chris Williamson following his controversial readmission to the party.
There was widespread anger over Wednesday’s announcement that the Derby North MP has had his suspension lifted amid criticism at the way the party deals with allegations of antisemitism.
In a statement signed by 90 Labour MPs and peers, Tom Watson said they could not overstate the "depth and breadth of hurt and anger" at the way the case had been handled.
"We call on Jeremy Corbyn to show leadership by asking for this inappropriate, offensive and reputationally damaging decision to be overturned and reviewed," the statement said.
"Ultimately, it is for Jeremy Corbyn to decide whether Chris Williamson retains the Labour whip.
"He must remove it immediately if we are to stand any hope of persuading anyone that the Labour Party is taking antisemitism seriously."
Mr Williamson - a prominent ally of Mr Corbyn - was suspended in February following his claim the party had been "too apologetic" in response to criticism over its handling of antisemitism allegations.
Following a hearing of a National Executive Committee (NEC) antisemitism panel, he was issued with a formal warning but allowed back into the party.
The statement was signed by 90 Labour politicians
In their statement, the Labour parliamentarians said the panel had ignored a recommendation Mr Williamson should be referred to the National Constitutional Committee for action.
They also said that the composition of the panel had been changed at short notice in a way that seemed "highly irregular".
Campaigning in Hartlepool, Mr Corbyn defended the way the case was dealt with and said the party took all allegations of antisemitism "very, very seriously".
"I wasn't involved in the decision at all, it was an independent panel set up through the National Executive, they examined the case and they've decided to let him back in, albeit with a reprimand,” he said.
"Anyone that makes antisemitic remarks can expect to be at the very least reprimanded and, if they are very serious and they engage in antisemitic activity, then they are expelled from the party."
The panel's ruling was welcomed by Mr Williamson who said he had received an "avalanche" of good will messages from grassroots party members.