Deputy Labour leader Tom Watson has urged an “amnesty” for party members who voted Liberal Democrat or Green in the European elections.

He attacked “spiteful” moves to expel people like former Blair spin doctor Alastair Campbell after they admitted backing rival parties in the poll last week.

Campbell was sent an email by Labour’s HQ informing him he had automatically expelled himself by declaring on BBC TV on election results night that he had voted for Vince Cable’s party.

But Watson, who is pushing for members to formally be allowed to toughen up Labour’s policy on a second Brexit referendum, said that thousands of supporters had sent Jeremy Corbyn a similar message in the elections.

To back clearly pro-Remain parties, some Labour members in Scotland voted SNP, in Wales they voted Plaid, but across England many backed the Lib Dems or Greens.

“It is very clear that many thousands of Labour Party members voted for other parties last week. They were disappointed with the position on Brexit that a small number of people on the NEC inserted into our manifesto,” Watson said in a statement.

“They were sending the NEC a message that our position lacked clarity and they were right. It is spiteful to resort to expulsions when the NEC should be listening to members.”

He added that the “politics of intolerance” holds no future for the Labour Party. “A broad church party requires pluralism and tolerance to survive. There should be an amnesty for members who voted a different way last week. We should be listening to members rather than punishing them.”

HuffPost UK has been told by members that some constituency Labour parties (CLPs) were advised by the party’s HQ to report to the compliance unit anyone who publicly admitted voting Lib Dem or Green. However, a party spokeswoman said such claims were ‘not true’.

Labour emailed Campbell on Tuesday to tell him that his actions were “incompatible with party membership”. 

The former No.10 strategy and comms chief, who has been a long-standing advocate for a so-called people’s vote on EU membership, tweeted that he was “sad and disappointed” by the news – and that he may launch a legal challenge. 

A growing #expelmetoo campaign emerged on Tuesday night after Campbell’s expulsion.

Former party rulebook chief Mike Creighton leapt to Campbell’s defence, stating that declaring a vote for a party after a poll had closed was not considered a breach of membership.

His view was echoed by former deputy leader Harriet Harman.

Creighton’s verdict followed claims by some Corbyn supporters that the party rules meant ‘auto-exclusion’ for anyone who ′supports a political organisation other than an official Labour group’

The party itself made a distinction between voting for a rival party and publicising that vote, as a form of promotion of another party.

In a new blogpost on Wednesday, Creighton said that the Labour press statement proved that any residual case for justifying Campbell’s expulsion had now ‘collapsed’.

The former director of Labour’s governance and legal unit said: “It is not possible to support another candidate (the essential allegation) after the polls have closed.

“One thing is certain. This was not a decision taken by an officer of the Governance and Legal Unit on Bank Holiday Monday.

“This wasn’t a decision about an unknown party member who had stood against an official Labour candidate at some local election. This was about a prominent member of the Labour Party with a significant public profile. This would have been a decision taken at the highest possible level.”

Former Labour home secretary Charles Clarke called on Labour to reinstate Alastair Campbell, as he admitted he also voted Liberal Democrat in the European elections

Clarke, a senior figure in the New Labour government, said he took a “one-off decision” to vote for the Lib Dems in the recent European Parliament elections.

Campbell claimed that ‘senior’ figures Corbyn’s leadership team had in the past recommended voting for other parties and had not been expelled.

“I think that there are people in Jeremy Corbyn’s office, senior positions in Jeremy Corbyn’s office, who have recommended voting against the Labour Party,” he said.

“You can interpret the rules in all sorts of different ways, but one thing I know is I’m not going to leave the party just because some random email comes in telling me that I’ve been expelled.”