Jeremy Corbyn, a Parliament member who is on track to become the head of Britain’s Labor Party, wrote a letter in support of a priest who claimed that Israel and wealthy Jews were behind the 9/11 attack on the World Trade Center.

Corbyn defended Rev. Stephen Sizer, who in February posted an article on Facebook blaming Israel for the attack on the New York landmark, the Daily Mail reported Wednesday.

In a letter to Anglican Church leaders after they decided to ban Sizer from using the Internet for six months, Corbyn wrote in February 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.” Corbyn has surprised many by leading in the race for Labor chief in polls of party members this summer.

According to the Daily Mail, he also has described Hamas and Hezbollah as his “friends” and is a close friend of Holocaust denier Paul Eisen, who runs a pro-Palestinian group called Deir Yassin Remembered.

In a blog post referenced by the Daily Mail, Eisen claimed that he and Corbyn had been close for 15 years, that Corbyn attended his group’s anti-Israel events each year and that the Parliament member had donated money to the group.

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 frequently on a Hezbollah television station.