A dispute over accusations of anti-Semitism within the ranks of Britain’s Labour Party escalated on Thursday as the party suspended Ken Livingstone, a former mayor of London, over remarks suggesting that Hitler had at one point supported Zionism.
Mr. Livingstone is an ideological ally of the Labour leader, Jeremy Corbyn, who on Wednesday took action against one of his lawmakers, Naseem Shah, in a separate dispute over comments on Facebook about Israel.
A well-known personality who has often defended Mr. Corbyn, Mr. Livingstone is not a member of Parliament but leads the international policy commission of Labour’s National Executive Committee, its governing body. His suspension comes as a blow to Mr. Corbyn, who has been accused of failing to root out anti-Semitism within the party. The left wing of the Labour Party, to which both Mr. Corbyn and Mr. Livingstone belong, has long been critical of Israeli policy toward the Palestinians – something its members argue should not be confused with anti-Semitism.
The latest dispute occurred in the aftermath of Wednesday’s decision to suspend Ms. Shah, pending an investigation, after it emerged that in 2014, before entering Parliament, she had endorsed a Facebook post displaying a graphic that showed Israel’s outline superimposed on a map of the United States. The map was under the headline, “Solution for Israel-Palestine conflict – relocate Israel into United States,” with the comment, “Problem solved.”
Ms. Shah added a note suggesting the plan might “save them some pocket money.”
Though Ms. Shah has apologized, Mr. Livingstone inflamed the situation when he was asked in a BBC interview about her suspension on Thursday.
“Let’s remember, when Hitler won his election in 1932, his policy then was that Jews should be moved to Israel,” Mr. Livingstone said. “He was supporting Zionism before he went mad and ended up killing six million Jews.”
Mr. Livingstone also said that there had been an attempt to “smear Jeremy Corbyn and his associates as anti-Semitic from the moment he became leader.”
Later on Thursday, Mr. Livingstone was confronted by John Mann, a Labour lawmaker, who in a series of angry exchanges filmed outside a television studio described him as a “disgusting Nazi apologist” and accused him of “rewriting history.”
Worries about the stance of the party’s leadership had already led to criticism from one Labour donor, David Abrahams, who told the British newspaper Jewish News that he had been “appalled by the growth of anti-Semitism in the party,” describing it as “a plague that has to be stamped out.”
Moshe Kantor, president of the European Jewish Congress, appealed to Mr. Corbyn to institute a zero-tolerance policy toward anti-Semitism.
“Corbyn has to answer why there are special criteria for anti-Semitism as if it is somehow considered a more acceptable form of racism, discrimination and bigotry,” he said in a statement.
Mr. Livingstone is no stranger to controversy and has been one of the most acerbic figures on the left wing of the Labour Party for several decades. When he was not selected by Labour to run for the London mayoral elections in 2000, he entered as an independent and won – though when he was re-elected in 2004, it was as the official Labour Party candidate.
In 2005, Mr. Livingstone was investigated for likening a Jewish reporter to a Nazi concentration camp guard. Last year he provoked criticism when he said that a Labour lawmaker, Kevan Jones, who has depression, “might need some psychiatric help” – though he eventually apologized for the comment.
Among those who had called for disciplinary action against Mr. Livingstone over his latest remarks was Sadiq Khan, a former Labour government minister who hopes next week to be the first Muslim to be elected mayor of London.
In a statement, the Labour Party said that Mr. Livingstone had been suspended “pending an investigation, for bringing the party into disrepute.” It also added that Mr. Mann – the lawmaker who confronted Mr. Livingstone – had been summoned by the chief whip, who is responsible for parliamentary discipline, “to discuss his conduct.”
Mr. Corbyn also told reporters that the Labour Party was “not tolerating anti-Semitism in any form whatsoever in our party.”
Yet the recent episodes may weaken Mr. Corbyn, who is at odds with many of his own lawmakers. A clear majority of them did not want him to be their leader despite his winning an overwhelming mandate from party members and supporters last year.
Mr. Livingstone is one of relatively few experienced political figures upon whom Mr. Corbyn can rely for support on issues that put him at odds with many of his lawmakers, such as his opposition to nuclear weapons.
The rift also exposed political divisions within the opposition ranks, as one of Mr. Corbyn’s critics attacked him for taking action against Mr. Mann, as well as Mr. Livingstone.
Michael Dugher, who was fired this year by Mr. Corbyn as Labour’s spokesman for culture, media and sport, supported Mr. Mann on Twitter, saying: “What on earth has happened to the Labour Party?”