Image copyright PA
Frank Field was one of 26 MPs to nominate Jeremy Corbyn for the Labour leadership in 2015
Frank Field has told constituents he quit the Labour whip because of the party's "appalling culture".
The veteran MP, who has represented Birkenhead for nearly 40 years, said under Jeremy Corbyn's leadership it was now "a party where anti-Semitism is more than tolerated".
He wrote in the Liverpool Echo it was with "considerable sadness" he left the party's group in Parliament.
A Labour Party spokesman thanked Mr Field for his service to Labour.
Mr Field had been among the MPs to nominate Jeremy Corbyn for leader in 2015, but said he did so to ensure a "broad debate" on the leadership, and never expected him to win.
"My wish to see a more inclusive debate in the Labour Party could not have been more wide of the mark," he wrote.
He is expected to meet Labour's chief whip Nick Brown on Friday to discuss his options, having said he wishes to serve as an independent MP while remaining a member of the party. Labour sources have said this will not be possible, however.
Under the Parliamentary Labour Party standing orders, which governs MPs, anyone who takes such action as Mr Field will usually receive a letter asking them to retake the whip within two weeksor face expulsion.
Mr Field quit the party's parliamentary group through a letter to Mr Brown on Thursday, saying the leadership is becoming "a force for anti-Semitism in British politics".
Field: We must deal with 'local Labour thuggery'
The MPwho lost a confidence vote in his constituency party last month over his pro-Brexit stancealso blamed a "culture of intolerance, nastiness and intimidation" in local parties.
Jeremy Corbyn has apologised for hurt caused by anti-Semitism in the party and pledged to stamp it out.
A Labour source claimed that "Frank has been looking for an excuse to resign for some time".
In the article for his local newspaper, Mr Field said the reason he was one of the 36 MPs to nominate Mr Corbyn for the party leadership was "to be inclusive of the hard left, as these views have a legitimate place in Labour thinking".
But he also said: "Following Jeremy's election as leader and the growth of party membership, which would in normal circumstances be welcome, we have become a party that displays intolerance, nastiness, and intimidation at all too many levels."
Complaints 'met with silence'
Mr Field said his constituency party was characterised by "sheer thuggery and blatant bullying" with "racist, ageist and s3xist" intolerance.
He also said his complaints to the national party about it had been "met with silence" and such behaviour "is a cause for shame and is unacceptable" to him.
Mr Field, the one-time minister for welfare reform, lost a confidence vote by his constituency party after voting with the government over Brexit plans.
On Thursday, he denied he was "jumping before being pushed" and used the article to further condemn some local members.
He repeated that he would remain a member of Labour but added: "I cannot, through continuing to take the Labour whip, lend any legitimacy to the most appalling culture which is now dominating national and local Labour Party institutions."
Birkenhead voters react to local MP Frank Field's decision to resign the Labour whip
Mr Field concluded the article by calling for two "major changes".
"First, the current excuses for its blatantly racist toleration of anti-Semitism must cease and we need to regain our position as being the leading force against racism in this country," he wrote.
"Second, the party must recognise the culture of intolerance, nastiness and intimidation that it has allowed to grow unchecked and expel local members whose public conduct is simply disgraceful."
Praise and criticism
A number of Mr Field's Labour colleagues have praised him and expressed their own concerns about their party.
Labour's deputy leader Tom Watson described the resignation as a "serious loss to the party" and a "major wake up call".
MP Mary Creagh said the fact Mr Field's local party wanted to deselect him "speaks volumes about the state of our party".
And fellow MP Siobhain McDonagh has described Frank Field as "a Labour warrior", telling BBC's Newsnight: "Don't we want in our politicians and our MPs mavericks who are prepared to stand up and say it as it is?"
He was also applauded by some Conservative MPs, with Home Secretary Sajid Javid tweeting that he was "a man of integrity and principle".
But Corbyn-supporting members of Labour have criticised Mr Field's decision.
MP Chris Williamson denounced his colleague's comments as "grotesque slurs, which have no basis in reality".
He told Newsnight: "The party has taken the issue of anti-Semitism very seriously; far more seriously than any other political party.
"It's so sad to see someone like Frank Field trashing Labour's anti-racist record".
And Labour's shadow justice secretary Richard Burgon said Mr Field should face a by-election.