Labour will investigate after dozens of antisemitic messages were sent to non-Jewish MPs who have criticised party leadership candidate Jeremy Corbyn.
John Mann, chairman of the All-Party Parliamentary Group Against Antisemitism, said he had received more than 40 abusive emails and tweets in the past six weeks.
They referred to him as “utter filth” and a “Zionist stooge”.
Mr Mann has been vocal in his opposition to Mr Corbyn’s campaign to lead the party. He claimed the abuse was coming from supporters of the favourite to be leader.
Read: The key questions Jeremy Corbyn must answer
On Sunday Mr Mann re-tweeted a number of the messages, including some suggesting he was under the influence of Israel.
He said other Labour supporters had sent him tweets to report similar abuse, including from Jewish party members who had been accused of dual loyalty.
“I have very serious concerns about Jeremy Corbyn’s supporters,” Mr Mann told the Sunday Express. “I’ve received some vicious antisemitic abuse and I’m expecting the Labour Party to take action against this.
“This began six weeks ago when I challenged the membership system. I said it was crazy. This was something I’ve done several times, including in Parliament on May 10, before Corbyn was a leadership candidate.
“I warned the system would lead to all sort of groups joining in. It is a mad system open to abuse by everyone, from the far-right to the far-left.
“It seems I was right. I have been described as a servant of the Israeli Prime Minister, a Nazi Zionist, a Zionist scumbag. This is all because I chair the All-Party Parliamentary Group Against Anti-Semitism.”
Mr Mann said many of those sending abuse had openly expressed their support for Mr Corbyn.
He said other non-Jewish MPs, including leadership candidate Liz Kendall and new Labour Friends of Israel chair Joan Ryan were among those targeted for antisemitic abuse.
Mr Corbyn said last week that there “should not be any antisemitic, Islamophobic or racist slogans or banners at any demonstration, ever”.
In a major speech in London on Sunday, former Labour Prime Minister Gordon Brown made a veiled reference to Mr Corbyn's positions.
Although not mentioning the MP by name, Mr Brown said: "I have to say that if our global alliances are going to be alliances with Hezbollah and Hamas and Hugo Chavez's Venezuela and Vladimir Putin's Russia, there is absolutely no chance of building a world-wide alliance that can deal with poverty and inequality and climate change and financial instability, and we've got to face up to that fact."
Mr Corbyn has previously described Hezbollah and Hamas as "friends".