Labour MP Kate Osamor has been suspended by her party after saying Gaza should be remembered as genocide in a post about Holocaust Memorial Day.
The Edmonton MP has since apologised for “any offence caused” over the message distributed to local party members on Friday.
Jewish groups have criticised the remarks.
The chief whip suspended her from the parliamentary party while an investigation takes place.
Holocaust Memorial Day (HMD) marks the six million Jews and other groups murdered during the Holocaust, alongside recent genocides.
Ms Osamor had shared a photograph of herself at a Holocaust Educational Trust event.
She wrote: “Tomorrow is Holocaust Memorial Day, an international day to remember the six million Jews murdered during the Holocaust, the millions of other people murdered under Nazi persecution of other groups and more recent genocides in Cambodia, Rwanda, Bosnia and now Gaza.”
She later tweeted an apology “for any offence caused by my reference to the ongoing humanitarian disaster in Gaza as part of that period of remembrance”.
BBC News has approached Ms Osamor for comment.
The Holocaust Educational Trust described her remarks as a “painful insult to survivors of the Holocaust”.
The Board of Deputies of British Jews called her comment “disgraceful”, while the Jewish Leadership Council accused her of abusing HMD to attack the Jewish state.
Shadow business secretary Jonathan Reynolds said it was not acceptable to equate the Holocaust to the situation in Gaza.
“What is happening in Gaza is clearly a humanitarian catastrophe that is recognised. But there are specific reasons why the Holocaust is considered as it is,” he told Sky News.
Momentum, the pressure group on the left of Labour, called the suspension an “outrageous decision” following a ruling by the UN’s top court.
The International Court of Justice (ICJ) ordered Israel to take all measures to prevent genocidal acts in Gaza but stopped short of telling it to halt the war.
A verdict on the central allegation of genocide is expected to take much longer, possibly years.
The 7 October attacks killed about 1,200 people in southern Israel. More than 100 of the 240 hostages who were snatched and taken to Gaza remain in captivity.
Meanwhile, Israel’s air and ground assaults in the Palestinian territory have killed more than 25,000 people, the Hamas-run health ministry in Gaza says.
Labour has urged Israel to comply with the ICJ’s ruling on the war, but leader Sir Keir Starmer’s position on Israel – supporting its right to defend itself, and later calling for a sustainable ceasefire over the “intolerable” situation – has caused tensions within the party.
Ms Osamor, who served as shadow international development secretary under Jeremy Corbyn, is the second Labour MP to apologise for remarks about the war in Gaza in a week.
During Prime Minister’s Questions, Tahir Ali accused Rishi Sunak of having “the blood of thousands of innocent people on his hands” due to his response to the conflict.
The Birmingham Hall Green MP later tweeted an apology “for the way in which I described the prime minister in my question”.
A Labour spokesman called his remark “clearly inappropriate”.
