"The conclusion of these books is that animosity toward Jews was not because of their religion, but because of their social activities", including money-lending, he said, parroting common anti-Semitic tropes.
"The proof of this is that there were Jews [living] in all Arab countries", Abbas said, going on to assert that Jews had lived in the Arab world for some 1,400 years without facing religious persecution. But why did this happen? "They say 'it is because we are Jews'".
During the four-day conference, Palestinian President Abbas also told the PLO Parliament, that he plans to take unspecified "tough steps" soon against Israel and the United States.
"President Abbas has repeatedly referred to the Holocaust as the most heinous crime in history", said Erekat.
Friedman and Abbas have sparred before.
He added: "President Abbas has shown a commitment to non-violence and a two-state solution".
Denying Jewish identity and Jewish rights to any part of Israel are other forms of anti-Semitism that Abbas frequently embraces.
An the UN's special coordinator for the Middle East accused Abbas of repeating "contemptuous anti-Semitic slurs".
Greenblatt said the comments were "very unfortunate, very distressing & terribly disheartening". The long-moribund peace process remains moribund. Ties have been strained since Trump recognized Jerusalem as Israel's capital previous year, prompting the Palestinians to suspend contacts with the administration.
On Wednesday, the European Jewish Congress called on European leaders and officials to cease all contact with the Palestinian leader until he apologizes for his outrageous anti-Semitism and Holocaust denial.
The Palestinians tried unsuccessfully on Thursday to refocus the debate on the Israeli "occupation", as condemnation of Abbas's speech in Ramallah continued to roll in. "Is that anti-Semitism or political discourse?"
The Dutch Foreign Ministry said Abbas's speech was "unacceptable". "His time as a Palestinian leader who can be considered a possible partner for any kind of peace negotiation is over".
Netanyahu's office responded by accusing Abbas of disseminating "a blood libel".
Mr Abbas, 82, is thought to have achieved most of his goals at the meeting, including the removal from the committee of some of his rivals, including Yasser Abed Rabbo and former Palestinian Authority prime minister and negotiator Ahmed Qurei.
Another allegation from the Middle Ages - that Jews murdered Christian children to use their blood for ritual purposes - gave rise to the term "blood libel".
The accusation that Jews were poisoning the wells of Christians gained traction in 14th century Europe as a plague swept across the continent.