Jeremy Corbyn, a left-wing British MP on track to become the head of the main opposition Labour Party, is coming under increasing scrutiny for his apparent ties to figures with anti-Semitic and anti-Israeli views, including 9/11 conspiracy theorists who blame the attacks on the Jews.

Earlier this year Corbyn wrote a letter in support of a priest who claimed that Israel and wealthy Jews were behind the terror attack on the World Trade Center. At a 2014 pro-Palestinian event in Parliament organized by Corbyn, an activist who has claimed Jewish elders control the world’s finances was allowed to speak, and called for the arming of Palestinian militias. Another anti-Israeli activist at the event compared the Jewish state to Nazi Germany.

Corbyn has referred to terror groups Hamas and Hezbollah in the past as “friends.”

Get The Times of Israel's Daily Edition by email and never miss our top stories Free Sign Up

The MP has gained a decisive lead over his rivals in polls ahead of the election of the new Labour chief, being held because party leader Ed Miliband quit following a crushing defeat to David Cameron’s Conservatives in May. A recent YouGov survey had Corbyn winning 53 percent of the vote, a staggering 32 points ahead of his closest rival, Andy Burnham. Corbyn was originally seen as a dark horse candidate holding views too radical to enable him to win the party leadership.

This led former Labour prime minister Tony Blair to warn voters on Wednesday that the party faced “annihilation” if Corbyn was elected leader. In an opinion piece for the Guardian, Blair contended that Corbyn could not possibly win a general election.

“The party is walking eyes shut, arms outstretched, over the cliff’s edge to the jagged rocks below,” he said.

Corbyn in February defended Rev. Stephen Sizer, who posted an article on Facebook blaming Israel for 9/11, the Daily Mail reported. In a letter to Anglican Church leaders after they decided to ban Sizer from using the Internet for six months, Corbyn wrote that Sizer was unfairly “under attack by certain individuals intent on discrediting the excellent work [he] does in highlighting the injustices of the Palestinian Israeli situation.”

Sizer had been accused of anti-Semitism even before his February Facebook post. In 2014 he delivered a speech on the “Israeli lobby” at an Iranian conference that sought to “unveil the secrets behind the dominance of the Zionist lobby over US and EU politics,” according to the Daily Mail. He has also visited Hezbollah leaders in Southern Lebanon and appeared on a Hezbollah television station.

Holocaust denier Paul Eisen, who runs a pro-Palestinian group called Deir Yassin Remembered, has claimed to be a close friend of Corbyn. In a blog post referenced by the Daily Mail, Eisen said he and Corbyn had been close for 15 years, that Corbyn attended his group’s anti-Israel events each year, and that the MP donated money to the group.

The Corbyn campaign denied this, saying “Paul Eisen clearly holds some of the most extreme views that are entirely his, and Jeremy totally opposes them and disassociates himself from them.”

During an October 2014 event in Parliament organized by the Labour MP, far-right activist James Thring reportedly seized the stage during a lull and spoke of the need to arm Palestinians against Israel. Thring has also spoken in the past of “Jewish elders” who control the world financial system.

Corbyn later said Thring’s speech was unscheduled and unsanctioned by him.

Anti-Israeli activist Max Blumenthal, who Corbyn did invite to speak at the event, called Israel a “racist society” and compared treatment of African immigrants in the country to “Kristallnacht” — the 1938 Nazi pogrom against German Jews in which dozens were murdered.

During a 2009 speech Corbyn gave as patron of the Palestine Solidarity Campaign, the candidate invited members of Hamas and Hezbollah to address Parliament.

“It will be my pleasure and honor to host an event in Parliament where our friends from Hezbollah will be speaking,” he said at the time. “I’ve also invited our friends from Hamas to come and speak as well… So far as I’m concerned, that is absolutely the right function of using Parliamentary facilities.”

In July Corbyn attempted to clarify his position, insisting that he used the word “friends” in “collective way” to describe the extremist Islamist organizations, but did not endorse their views.

“I’m saying that people I talk to, I use it in a collective way, saying our friends are prepared to talk,” he said.

“Does it mean I agree with Hamas and what it does? No. Does it mean I agree with Hezbollah and what they do? No. What it means is that I think to bring about a peace process, you have to talk to people with whom you may profoundly disagree,” he said.

Britain’s pro-Israel community is viewing the race for the Labour Party leadership with concern after the UK’s biggest union, Unite, threw its weight behind Corbyn.

Corbyn, MP for the inner city London constituency of North Islington since 1983, was a surprise addition to the leadership race, set for a September vote. But Corbyn’s very difference from the other candidates — former health secretary Burnham, Shadow Home Secretary Yvette Cooper (wife of ousted shadow chancellor Ed Balls, who lost his seat in the May election), and Shadow Health Care and Older People Minister Liz Kendall — has brought him into prominence.

Commentators say that where Israel is concerned, Burnham is the candidate most obviously akin to Labour’s former leader Miliband, who led the party to an unexpectedly heavy defeat to Cameron’s ruling Conservatives in May.

Not very interested in foreign policy, Burnham is said to be basically sympathetic to the Palestinians but opposed to boycotts. Labour Friends of Israel supporters such as MPs Michael Dugher and Luciana Berger have backed his nomination, although in March, after the Israeli elections, Burnham tweeted that Benjamin Netanyahu’s re-election meant that “Palestine will need more international support.”

Cooper and Kendall are thought to be marginally more pro-Israel, particularly Cooper, who is said to “get” the anxieties of the Jewish community.

Ballot papers go out on August 14 and must be returned by September 10. On September 11 the leadership result will be announced.

Jenni Frazer contributed to this report.