The BBC has admitted that it failed to sufficiently challenge an Iranian guest who accused Israel of being an “ethno-supremacist” state that is committing a “holocaust” in Gaza.

Mohammad Marandi, a professor at the University of Tehran, appeared on Radio 4’s flagship show on Tuesday to comment on how Iran would respond to Israel’s “limited” ground invasion inside Lebanon.

In what Jewish organisations called a “disgraceful” move, Mishal Husain, the BBC presenter, permitted Mr Marandi to speak at length, unchallenged, as he called Israel a “genocidal regime” that believed its citizens were the “chosen people”.

A BBC spokesperson told The Telegraph that Mr Marandi was interviewed to “gain an understanding of the view from Iran” and noted that he “was challenged during the course of the interview and the Israeli position was reflected”.

They added: “However, we accept we should have continued to challenge his language throughout the interview.”

The BBC is facing a wave of criticism for allowing what commentators have called “offensive” anti-Semitic tropes to be broadcast on its airwaves largely interrupted.

Husain only appeared to interrupt him once to ask what he meant by Iran will do “whatever it takes” to stop Israel. Mr Marandi skirted around the question, saying: “I’m not part of the Iranian government.”

The Iranian-American academic, who is the son of the former Iranian health minister, has previously been called a “propagandist” and “mouthpiece” for the Iranian regime by HonestReporting, an organisation that works to combat prejudices in the media.

The BBC, which “must remain duly impartial” according to its own guidelines, allowed Mr Marandi to continue uninterrupted as he claimed that the “UK supports this Holocaust in Gaza, just as it supports the slaughter of the Lebanese”.

“We have no doubt that [the UK] will be with the Israelis until the very last Palestinian,” he said, adding that the only way forward was “resistance” by Iran’s proxy forces.

The professor then labelled Israel an “expansionist regime” that “believes in ethno-supremacism”, without rebuttal from Husain.

“It believes that they are a chosen people. They have exceptional rights, and therefore they have exceptional rights to the whole region. It’s not just Palestine today. It goes beyond the borders of Palestine,” he added.

The presenter waited for Mr Marandi to finish, thanked him and moved on to a new segment of the show.

The Board of Deputies of British Jews said they were “deeply concerned” with the national broadcaster for allowing his claims to be aired “without clear pushback”.

“We will be raising this directly with the BBC at the highest levels,” it added in a statement.

Claudia Mendoza, the CEO of the Jewish Leadership Council, told The Telegraph: “Comments such as these are unacceptable and anti-Semitic, drawing upon ancient conspiracy theories about Jewish power and control.

“It is disgraceful for the BBC to air such comments, even more so given that they went unchallenged in a prime-time slot.”

Hadar Sela, the co-editor of the Committee for Accuracy in Middle East Reporting and Analysis (Camera), which lobbies for a fair representation of Israel in the media, said that for six years the BBC has solicited commentary from an “apologist for the Iranian regime”.

“No less unsurprising is the fact that BBC presenter Mishal Husain made no effort whatsoever to challenge Marandi’s racist rant and redundant claims of ‘genocide’,” Ms Sela told The Telegraph.

“This is not the BBC providing various viewpoints: this is the BBC knowingly providing a platform for lies and hate speech.”

Simon Schama, a historian and BBC presenter, called the Today’s Programme “profoundly and appallingly offensive” for allowing Mr Marandi to air his “anti-Semitic abuse about ‘chosen people’, ‘holocaust’ in Lebanon etc without challenge”.