The union that sits on the official Government Group on Antisemitism and Higher Education is facing calls for its expulsion because it hosted a man who made an antisemitic speech.

The University and College Union (UCU) invited Bongani Masuku, international secretary of the Congress of South African Trade Unions (Cosatu), to tour UK universities this week and to speak at an invitation-only conference last Saturday, arguing for a boycott of Israel.

But just 48 hours earlier, the South African Human Rights Commission (HRC) found that there was a “prima facie case of hate speech” following threats to Jews in a speech Mr Masuku made in March at Witwatersrand University.

In it, he said: “We can make sure that for that side [Israel’s supporters] it will be hell. These people must face the consequences even if it means that we will do something that may necessarily cause what is regarded as harm… Any South African family who sends its son or daughter to be part of the Israeli Defence Force must not blame us if something happens to them with immediate effect…”

The South African Board of Deputies (SAJBD), which lodged the complaint with the Human Rights Commission, also cited a blog in which Mr Masuku wrote: “We struggle to liberate Palestine from the racists, fascists and Zionists who belong to the era of their Friend Hitler! We must not apologise, every Zionist must be made to drink the bitter medicine they are feeding our brothers and sisters in Palestine.”

The Human Rights Commission ruled that Mr Masuku “uttered numerous antisemitic remarks”. It held that he “incited violence and hatred” by calling for Jews to be “despised, scorned and ridiculed”.

In Britain, the Board of Deputies wrote to Home Secretary Alan Johnson asking for Mr Masuku to be banned. That request was turned down.

The Board, the Jewish Leadership Council and the Community Security Trust have now called for UCU to be removed from the government advisory body. They declared: “As the largest union in further and higher education and a self-proclaimed campaigner against racism, it is irresponsible and grossly offensive of UCU to bring Bongani Masuku to the UK, given his track record.

“UCU has chosen to connect its boycott activities to antisemitism…It appears that UCU simply does not care about the anti-Jewish impact of its activities.

“The government should review UCU’s membership of this group as it has failed to oppose antisemitism inside its own structures. UCU cannot credibly be a part of the solution to antisemitism while its activities are encouraging the problem.”

Mr Masuku was one of three guests from abroad. He was accompanied by former South African government minister Ronnie Kasrils, who is Jewish, and Palestinian activist Omar Barghouti. It is believed that Mr Masuku returned to South Africa in the wake of the HRC ruling.

There was evidence that the HRC was coming under pressure to revisit its decision. Its spokesman, Vincent Moaga, said what had been published was only a draft.

But David Saks of the SAJBD said: “That’s news to me. It’s been in all the papers since last week and there’s not been a murmur of protest from the HRC. I think they could be under pressure from a number of groups who don’t like the decision.”

A UCU spokesperson said: “Our understanding is that Mr Masuku is seeking a proper hearing in relation to complaints around comments he made back in March. Until that process is properly complete it is not really appropriate for UCU to comment.”