A series of Labour members have been suspended from the party for attacks on Israel and allegations of Jew-hate.
Mr Regev said: “We’ve seen definitely some language over the last few weeks which is very concerning.
“If you’re saying...the Jewish people don’t have that right...to sovereignty and independence, you have to ask why you are holding Jews to a different standard. And there is a word for that.
“Of course they have the right to criticise the government of Israel. Israeli people do that every day. It’s not about criticising Israel. It’s about demonising the Jewish state.
“The comments of the past few weeks are demonising, a vilification of my country and its very right to exist. There’s a difference between legitimate criticism and hate speech. Hating Jews is a red line that cannot be crossed.”
Asked by Mr Marr whether the line had been crossed in recent weeks, Mr Regev said: “Definitely.”
He said modern antisemites target “the collective Jew”.
Mr Regev also attacked progressive politicians who had “embraced Hamas”.
“There has to be an unequivocal message from leadership saying there is no solidarity with antisemites. It is crucial leaders say this is unacceptable. Why can you share a platform with someone who is antisemitic?”
Speaking on the same programme, Shadow International Development Secretary Diane Abbott claimed it was "something of a smear to ordinary Labour party members to say Labour has a problem with antisemitism. Antisemitism is a problem right across Europe".
Ms Abbott said she took antisemitism seriously because of the large Charedi community in her Hackney constituency.
Mr Marr said: "Something has gone wrong, the Board of Deputies thinks something has gone wrong, the Jewish Chronicle thinks something has gone wrong, the ambassador thinks something has gone wrong, and your party has set up an inquiry."
Yesterday, Isaac Herzog, leader of the Israeli Labour Party, invited his UK counterpart to visit Israel and its Yad Vashem Holocaust museum to learn about antisemitism and Holocaust denial.
The fall-out to the weeks of party Labour suspensions – the latest being Ken Livingstone, former London mayor – has seen rumours of MPs, unions and donors allegedly preparing the way for a serious challenge to Mr Corbyn, who has been leader of the party since September last year.
A so-called dossier put together by the Telegraph contained examples of what the newspaper called “antisemitic attitudes among party activists and leading members”.
It included a series of cases linked to Mr Corbyn which have previously been reported in the JC, including Mr Corbyn’s opposition to an antisemitic mural being removed from a property in east London , and details of his links to Holocaust denier Paul Eisen .
The Telegraph said Mr Corbyn had attended an event organised by Mr Eisen in April 2013, years after Mr Eisen had written an essay describing Shoah revisionists as “amongst the bravest people on the planet”.
A Labour council leader apologised on Saturday after he was shown to have shared a Facebook post which compared Israel to Daesh.
The party announced an independent inquiry into antisemitism and other forms of racism within the party on Friday.
Sadiq Khan, Labour’s candidate in Thursday’s London mayoral election, told the Observer he believed the row over Jew-hate could cost him the chance to lead City Hall.
“I accept that the comments that Ken Livingstone has made makes it difficult for Londoners of Jewish faith to feel that the Labour party is a place for them,” Mr Khan said.
Mr Livingstone refused more than 20 times on an LBC radio show on Saturday to apologise for his Hitler remarks.
He referenced the row over Israeli Prime Minister Benjamin Netanyahu’s comments last October about Hitler and the Grand Mufti of Jerusalem in the 1930s.
