Academics have voted to boycott two Israeli universities over their alleged involvement in "illegal activity" in the occupied territories.
Members of the Association of University Teachers (AUT) decided to suspend all links with Haifa and Bar-Ilan universities.
They were complicit in a system of "apartheid" towards Palestinians, delegates at the AUT's council heard.
The votes, and lack of debate, have been condemned by pro-Israel groups.
At the AUT conference, in Eastbourne, Haifa University was accused of mistreating politics lecturer Ilan Pappe for defending a graduate student's research into controversial areas of Israeli history.
His job had been threatened and he had been victimised, delegates in Eastbourne heard.
Bar-Ilan was accused of helping with degree programmes at a college in a settlement in the West Bank.
Sue Blackwell, an English lecturer from Birmingham University, said: "Most Israeli academics serve in the army's reserve forces.
"Most support the state's suppression of the Palestinians or at least don't speak out against it."
Delegates voted for more dialogue with Palestinian academics and unions.
However, they voted down a call by the union's executive to establish contact with a group called the Israeli Higher Education Union.
Ms Blackwell said that an internet search had found only six mentions of it, all linked with the AUT, and concluded that she did not think it existed.
The lecturers' decision has been criticised by representatives of the executives of Britain's universities, Universities UK.
A spokesperson said: "UUK condemns the resolution from AUT which is inimical to academic freedom, including the freedom of academics to collaborate with other academics."
AUT delegates called for an end to all co-operation with Haifa and Bar-Ilan and to discourage UK investment in them.
Israel's policies in the occupied territories were described as "colonial and racist".
However, another motion on boycotting the Hebrew University of Jerusalem - accused of building student dormitories on land confiscated from Palestinian families - was referred to the union's executive for further investigation.
A spokesman for the AUT said the union's executive would issue guidance to members on the implications of the votes.
Some delegates were annoyed that debate on the issue was curtailed due to a lack of time.
The universities could not immediately be contacted for a response to the AUT decisions.
But the Academic Friends of Israel in the UK said the boycott was "based on false information, imposes discriminatory boycott and vetting of political opinions, and is a backward step in the current climate of positive moves being made in the region".
"It is also the beginning of a dangerous process against the tenets of academic freedom and may rebound on the AUT itself," it said.
It also condemned the way that it had been made difficult for pro-Israel voices to be heard.
The group's chair, Ronnie Fraser, said: "Israelis and Palestinians will continue to co-operate even without the AUT, as they, who live the reality of the Middle East, know no other alternative is available for them.
"If the sponsors of this boycotting campaign succeeded in something, it is only to undermine further progress, collaboration and peace in the Middle East and to marginalise the standing of the AUT and its members in the academic community."
The Israeli Embassy in London said the resolutions were "as perverse in their content as in the way they were debated and adopted".
"The fact that no AUT member who wanted to argue against this decision was allowed to speak, and the case for the Israeli universities was not presented to delegates, speaks volumes about the relevance and fairness of this debate.
"Israeli universities are beacons of academic freedom where Jews and Arabs alike study together."