Former Harvard Law School professor Alan Dershowitz slammed former President Barack Obama over the weekend, following the revelation that the then-US Senator had met with Nation of Islam leader Louis Farrakhan on Capitol Hill more than a decade ago.

Last week, a photograph taken during a 2005 meeting between Farrakhan and Obama, then a freshly-minted US Senator from Illinois, was revealed to the public for the first time.

The photographer, Askia Muhammad, told Fox News Thursday night that the Congressional Black Caucus had arranged the meeting, and subsequently pressed Muhammad to conceal the photograph.

The picture shows a smiling Senator Obama standing side-by-side with Farrakhan.

Farrakhan, a controversial figure in the Black Muslim community in Chicago, has a history of using explicitly racist and anti-Semitic rhetoric.

In 1984, Farrakhan was recorded calling Judaism a “gutter religion”, leading the US Senate to condemn him in a unanimous 95-0 vote.

Farrakhan also called the establishment of the State of Israel an “outlaw act”, and accused the Jewish state of “thievery, lying, and deceit”.

'Now that nation called Israel never has had any peace in 40 years and she will never have any peace because there can be no peace structured on injustice, thievery, lying and deceit and using the name of God to shield your gutter religion under His holy and righteous name,” Farrakhan said in a June 1984 sermon.

In March of 1984, Farrakhan praised Nazi leader Adolf Hitler, calling him a “very great man”.

Despite years of criticism, Farrakhan never abandoned his anti-Semitic rhetoric, calling American Jews “satanic” in a 2013 sermon in Detroit.

According to the photographer behind the 2005 photograph, Askia Muhamad, then-Senator Obama employed people known to be members of the Nation of Islam on his senate staff.

"He had people from the Nation of Islam working on his staff in his office in Chicago - his senate staff,” Askia told Fox News. “Members of the Nation of Islam helped him in his senate campaign on the South Side of Chicago."

On Saturday, following the revelation, senior American jurist Alan Dershowitz excoriated former President Barack Obama for his meeting with Farrakhan, telling Fox News he would have refused calls to campaign on Obama’s behalf in 2008 had he been aware of the meeting.

“Louis Farrakhan is a virulent anti-Semite,” said Dershowitz. “He called Judaism a ‘gutter religion.’ He’s anti-American.”

“He is a horrible, horrible human being, and if I had known that the president had posed, smilingly, with him when [Obama] was a senator, I would not have campaigned for Barack Obama [in 2008]. It would have influenced my decision.”

Dershowitz, a lifelong Democrat, also noted the ties Democratic National Committee deputy chief Keith Ellison had with the Nation of Islam.

“I threatened to leave the party if Keith Ellison were elected as chairman because of his association with Farrakhan. You don’t associate with a bigot. You don’t associate with an anti-Semite. There should be zero tolerance for that kind of bigotry — and if Barack Obama associated with him, if the Black Caucus invited him, I don’t blame them for trying to suppress the truth because that’s a really horrible truth.”

In 2017, Dershowitz threatened to quit the Democratic party if Ellison were chosen to lead the DNC.