The manager of the Lewes Speakers Festival revealed last week he has been subjected to abuse over the booking of Katie Hopkins at the event.
Marc Rattray said he had been labelled ‘a cockroach’ online.
Ms Hopkins, the controversial television personality and columnist, compared migrants to cockroaches in a national newspaper column in 2015.
She is due to speak on Saturday, November 25, during the winter festival at The All Saints Centre in Lewes.
Mr Rattray reported ticket sales for her appearance had been “brisk”.
He said: “There are still tickets left though she is clearly popular with a couple of people taking flights to see her.”
There has been a furious local reaction to the booking with demands that her invitation be withdrawn. One commentator posted on social media: “As a town we should stand up and say we don’t want her hate speech here.”
Mr Rattray said: “To stop her speaking without good reason would be a violation of her human rights which are enshrined in domestic/ international law.
“One person labelled me a ‘cockroach’ online and another went to what they thought was my employer (incorrectly) to make a complaint. I have had quite a few supporters/ detractors by email. Katie Hopkins has said on the BBC that she is open to people saying whatever they like at the event.
“She is able to speak on the BBC both on radio and television and I personally don’t see any important difference between her speaking at the Lewes Speakers Festival and her speaking for them.
“I am simply promoting and defending free speech. The BBC may well film/ record the event.”
Ms Hopkins is due to discuss her book Rude, billed as a “hilarious and revealing talk” – part memoir, part advice for the modern woman
The festival website says: “Listeners be warned ... Katie doesn’t sugar-coat anything, and neither does she hold back.”
There will be a Question and Answer session.
A Sussex Police spokesman said: “We are aware of this event and have discussed it with the organisers who will be making security arrangements. It is not a matter for police to comment on any further at this time.”