Listeners to a late-night radio phone-in got a shock when a man introduced as a Zionist Federation spokesman announced he could not discuss Shimon Peres's comments on British antisemitism because he was eating a toasted sandwich.
The imposter, pretending to be former ZF public affairs director Gavin Gross, failed to answer any questions about Mr Peres's remarks, saying he was too busy eating.
TalkSPORT presenter Adrian Goldberg, not realising he had been hoaxed, said the man's comments were "absolutely, utterly disgraceful" during Sunday's show.
Mr Goldberg had asked the man: "What do you make of President Peres's comments?"
In reply, the man, speaking in a broad Scottish accent, would only say: "I don't really know. What do you think? Britain is terrible."
Eventually, the man was cut off and Mr Goldberg said: "My excellent and capable producer Natalie booked Gavin Gross earlier in the day. She is a producer in whom I have 100 per cent confidence. She is not an idiot, she is not a fool.
"We do think that was him [Gavin Gross]. To me the man is a disgrace to the Zionist Federation. He should be penning his letter of resignation and if he isn't he should be getting his
P45 in the post. If it was him… he is an utter idiot."
But the embarrassed presenter later back-tracked after a listener called the station to say an internet search for Mr Gross had revealed a JC story from September 2008 reporting that the American had made aliyah.
After the ZF contacted talkSPORT, the station issued an on-air apology at 11.30pm on Monday, and agreed to air an interview with the real Mr Gross on Wednesday morning.
Meanwhile, President Shimon Peres, whose comments on antisemitism in the UK had set off a flurry of tabloid and radio comment, issued a clarification of his remarks.
Mr Peres, 87, made the original comments to Israeli historian Benny Morris in the course of a wide-ranging interview for an American Jewish website, Tablet magazine.
He told Professor Morris: "In England there has always been something deeply pro-Arab, of course, not among all Englishmen, and anti-Israeli, in the establishment."
He also said that while Israel's relationships with Italy, Germany and France were "pretty good", England's attitude was Israel's "next big problem".
And, discussing foreign policy decisions, Peres said: "There are several million Muslim voters, and for many members of Parliament, that's the difference between getting elected and not getting elected."
But the remarks drew criticism from MPs and media commentators.
Romford MP Andrew Rosindell told the Daily Mail that the comments were "wholly inaccurate" and said Mr Peres should remember that British people "were at the forefront of defeating the Nazis in the Second World War."
The president, who was awarded an honorary knighthood by the Queen in 2008, denied he had meant the British were antisemitic.
His spokesman said: "On the contrary, he has the highest regard for Britain's resolute opposition to Nazi Germany. Without the war on Nazism, waged entirely alone at times, the Jewish people would have faced an even greater tragedy."
Pointing out that more than 10,000 missiles have been fired at Israeli civilians from Gaza, the spokesman added: "The president did express concern that some people in Britain do not fully appreciate the difficulties of facing an onslaught of terror whilst adhering to democratic practice, as Israel does."