The Union of Jewish Students has urged "strong action" to be taken after anti-Israel activists attacked their stall at the annual National Union of Students conference on Tuesday.

UJS staff returned to their stall to discover their logo had been covered with anti-Israel stickers, including over the star of David symbol. The stickers called for people to "boycott Israeli goods".

The incident took place after conference had mostly ended for the day and after UJS had packed up the stall. The vandalism was discovered after 9pm.

Writing on their blog, a UJS spokesman said that whatever a student's views on the Middle East, the conference should be "a safe space for all students".

He said: "There is no excuse for this behaviour within the student movement.

"The singling out of Jewish students and the direct attack on Jewish religious symbols is antisemitism."

UJS also called for strong action "to ensure that this incident is swiftly and appropriately dealt with".

The incident came not long after the Chief Rabbi addressed a large body of students from different backgrounds at the conference. He told them: "University is the school for justice and justice means giving a fair hearing to all.

"That is the precondition of justice. No group should feel intimidated at university."

The annual NUS conference is taking place in Sheffield this year, with more than 1,000 students from all over Britain taking part.

Liam Burns, NUS president, said: "NUS does not tolerate racism, fascism or antisemitism in any of its forms. Antisemitism is vile. It is hate and has no place in our movement.

"We will work day and night to drive hate out of our student movement, education system and society."

"We have of course launched a full investigation into this incident and will do all we can today to get to the bottom of it."

Lord Sacks said he was appalled to learn of what happened. "This was an act of antisemitism. The deliberate defacing of the star of David – a sacred symbol of Judaism and of the State of Israel – was an indication of the increasingly blurred line between anti-Zionism and antisemitism.

"It is part of a long, slow, insidious process intended to undermine academic freedom and it must not be tolerated."

A CST spokesman added: "We utterly condemn this crass attempt to intimidate and isolate Jewish students."