A group of peers has called on Scotland Yard to investigate online anti-Semitic abuse by supporters of Jeremy Corbyn.
The cross-party letter to Metropolitan Police Commissioner Cressida Dick highlights "unambiguous" examples of hate speech on Facebook groups set up to back the Labour leader.
Lord Sugar, who quit Labour three years ago, said Mr Corbyn was "dangerous" and insisted it was the Opposition leader's job "to stop inciting this type of rubbish".
He told the Daily Express: "I am happy to put my name to this letter. If I didn't know better, I would say Corbyn has deliberately aggravated the situation by associating himself with known haters.
"If you didn't condone it, you would keep away from it. If this was about Muslims there would be merry hell to pay, there would be riots in the streets."
Lord Sugar also posted an "ode to Jeremy Corbyn" on Twitter and called on MPs and peers to "grow a pair and get him OUT".
The letter to the Met was drafted by Lord Polak, honorary president of the Conservative Friends of Israel, and was backed by 10 other peers.
The letter states: "In one such example, the member of the Supporting Jeremy Corbyn & John McDonnell Facebook group said 'Adolph (sic), you should have finished the job'.
"This is a clear and unambiguous example of hate speech.
"One member of the Jeremy Corbyn Leads Us To Victory Facebook group posted pictures of journalists at the New York Times and CNN, with the Star of David pasted on to those they believed to be Jewish.
"It is our strongly held belief that this anti-Semitic rhetoric not only stirs up racial hatred which threatens the very fabric of community cohesion throughout London and the UK, but also poses a possible physical threat to the Jewish community."
A Met spokesman said: "The Metropolitan Police received correspondence addressed to the Commissioner's office on Wednesday 4 April and it will be reviewed."