Free speech on Israel is being suppressed by individuals and groups who deliberately seek to conflate criticism of the country with anti-Semitism, hundreds of academics have clamed.

In an open letter, professors at dozens of UK universities flagged concerns about the definition of anti-Semitism adopted by the current government, which they said universities Minister Jo Johnson asked be "disseminated" throughout the higher education system.

The International Holocaust Remembrance Alliance (IHRA) definition of anti-Semitism, currently favoured by Theresa May's party, “can be and is being read as extending to criticism of Israel and support for Palestinian rights," they said.

The conflict with Palestinians is "an entirely separate issue," and cannot be taken "as prima facie evidence of anti-Semitism", they added.

The IHRA says in its working definition of anti-Semitism: "Manifestations might include the targeting of the state of Israel, conceived as a Jewish collectivity. However, criticism of Israel similar to that levelled against any other country cannot be regarded as antisemitic."

The letter, signed by academics at the London School of Economics, Warwick, University College London, York, and Exeter universities, among others, asserts "this definition seeks to conflate criticism of Israel with anti-Semitism".

Published in The Guardian, the academics acknowledge a spike in far-right, anti-Semitic incidents on UK campuses, which “seems to reflect the increase in xenophobia since the Brexit vote”, but raise concerns about muddying the definition of anti-Semitism and restricting free debate on Israel.

In a letter to Universities UK, Mr Johnson “specifically mentions Israeli Apartheid Week (a worldwide activity at this time of year since 2005) as a cause for concern”, it says, adding this led institutions to cancel events.

“The response has been swift. Late last week, in haste and clearly without legal advice, the University of Central Lancashire banned a meeting that was to be addressed by journalist Ben White as well as by academics," the letter continues. "The university statement asserted that the meeting on “Debunking misconceptions on Palestine” contravened the definition of anti-Semitism recently adopted by the government, and would therefore not be lawful."

The Campaign Against anti-Semitism, a body set up during the Israeli assault on Gaza in 2014, cites the IHRA definition in asking its supporters to “record, film, photograph and get witness evidence” about Israeli Apartheid Week events, adding “we will help you to take it up with the university, students’ union or even the police”.

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In the letter, the academics describe the cancellation of the meeting in Lancashire and the statement by the Campaign Against anti-Semitism as “outrageous interferences with free expression,” and “direct attacks on academic freedom”.

The letter ends: “As academics with positions at UK universities, we wish to express our dismay at this attempt to silence campus discussion about Israel, including its violation of the rights of Palestinians for more than 50 years. It is with disbelief that we witness explicit political interference in university affairs in the interests of Israel under the thin disguise of concern about antisemitism.”

Israeli Apartheid Week is a series of events that seek to raise awareness about the country's "settler-colonial project and apartheid system over the Palestinian people”.

It also encourages people to boycott the country.

The 13th event kicked off in the UK this week and will happen in other countries around the world between March and April.

In a letter to the chief executives of the representative bodies for higher education institutions, Mr Johnson warned about an increased risk of anti-Semitic hate crimes ahead of the event.

“I am sure you share my concerns about the rising reports of anti-Semitic incidents in this country and will want to make sure that your own institution is a welcoming environment for all students and that the legal position and guidelines are universally understood and acted upon at all times," he said.

“This will include events such as those that might take place under the banner of ‘Israel Apartheid’ events for instance. Such events need to be properly handled by higher education institutions to ensure that our values, expectations and laws are not violated.”