The government-funded No Outsiders project, which works with 15 UK schools, has been running as a pilot since 2006 and provides gay story books such as King and King to schools, as well as helping teachers to organise plays, talks and films about gay families.
But Nick Griffin, leader of the British National Party, has described organisers of the project as "intellectual perverts".
Threats have since appeared on hard-right websites, with one blogger calling for "capital punishment for the paedo-intellectuals", alongside a list of researchers' names and contact details.
Several commentators compared the researchers to paedophiles. One said: "Personally, I think that authors of this monstrosity should be shot without any trial."
In response, plans for a public launch of the scheme, due this month, have been cancelled.
The TES removed all mention of schools involved in the scheme after Sunderland University expressed concern that they could be targeted by protestors.
The threats were made after The Daily Mail published a story claiming that the project's researchers wanted to "teach the pleasure of gay sex to children as young as five".
The article was a response to a conference organised by project leaders that looked at why educationists always fight shy of gay sex and "the negation of pleasure and desire in educational contexts".
What had been a dry academic debate about the nuances of addressing gay sexuality in schools turned into the basis for a misconception that gay sex was being taught in British primaries.
The Star alleged that puppets, books and plays would be used to "explain the `bodily' contact enjoyed by gays and lesbians".
But none of the No Outsiders projects, aimed at tackling homophobia, had involved discussing gay sex with pupils at all.
Primaries involved in the project said they understood the need to give it a lower profile but were still disapponted. "It's a shame," said one teacher. "But all this stuff about teaching gay sex . It's not true, but if parents read it, they could feel very let down."
Back in the closet, pages 20-21.