BuzzFeed explained it had brought the story to light following fresh allegations of antisemitism against Labour candidates in recent days.
But in a statement on Twitter, Mr Carden denied any suggestion of antisemitism, saying he had been “categorical in my denial about allegations relating to a coach trip some twenty months ago. This was a coach full of journalists and MPs.
“If anyone genuinely believed any antisemitic behaviour had taken place, they would’ve had a moral responsibility to report it immediately.”
He said the allegation had been only made now with an election imminent and he stood by his record as an anti-racist campaigner.
The Sunday Times, however, said it had obtained WhatsApp messages from the time of the journey that “appear to corroborate” Mr Wickham’s account.
The messages allege that Mr Carden had drunkenly joined in “antisemitic and homophobic” songs.
The paper reported that Labour Leader Jeremy Corbyn had promised to investigate, saying, “It’s an awful story. And if it is true, it is utterly unacceptable.”
Dave Rich, the CST’s head of policy, tweeted that Mr Carden’s response had been “strangely worded…If he didn’t sing it, just say so. And if he did, it’s irrelevant what anyone else did or didn’t do when they heard it.”
Labour’s problems with antisemitism allegations have already cost it three election candidates last week.
Chris Williamson, the former Labour MP for Derby North who was originally suspended last month for saying the party had been too apologetic on antisemitism, was disbarred by the party from contesting the seat next month.
Kate Ramsden, the candidate for Gordon in Scotland, stepped down after the JC exposed tweets in which she compared Israel to an abused child that had become an abusive adult and said antisemitic allegations against Jeremy Corbyn were being “orchestrated by the wealthy establishment”.
Clacton Labour candidate Gideon Bull dropped out after accusations he had called a fellow Haringey councillor who was Jewish “Shylock”.
He denied levelling it specifically at the councillor, explaining he had used it more generally against council backbenchers over a housing decision.
“When she politely informed me that this saying was offensive, I immediately apologised and explained that I did not know that Shylock was Jewish,” Mr Bull said.
Mr Williamson, however, has announced his intention to fight the election as an independent.
In a letter earlier this week, he described “antisemitism smears” against Labour activists, candidates and MPs as “unfounded”.
He said the party had capitulated to the Jewish Labour Movement, which had been revived four years ago at the same time as Israel “launched a diplomatic strategy to delegitimise Palestinian activism on the left”.
Labour Shadow Defence Secretary Nia Griffity, pressed over the party's antisemitism problems on the Sophy Ridge Show on Sky News on Sunday, said, "Where things come to light, we're making sure we do investigate and we do take action."
