Ethnic cleansing attended the birth of Israel but, more than 50 years later, the country is still in denial about its bloody past. Those who speak out risk their jobs.

Behind the turbulent news from Israel, a struggle for historical truth has passed almost unnoticed outside academic circles; yet its wider significance is epic. In May 1948, more than 200 Palestinians were killed by the advancing Jewish militia in the coastal village of Tantura, south of Haifa.

According to the recorded testimony of 40 witnesses, both Arab and Jewish, half the civilians were shot in a "rampage". The rest were marched to the beach, where the men were separated from the women and children. They were taken to a wall near the mosque where they were shot in the back of the head.

The "cleansing" of Tantura (a term used at the time) was a well-kept secret. When they were interviewed four years ago, several Palestinian witnesses said they feared for their lives if they spoke out. One survivor, who as a child witnessed the murder of his entire family in Tantura, said to the interviewer: "But believe me, one should not mention these things. I do not want them to take revenge against us. You are going to cause us trouble... "

Trouble indeed. The researcher, a student called Teddy Katz, has had his masters degree annulled by Haifa University, even though he was awarded a top grade by the Middle Eastern department. When his research was revealed in the Israeli press, Jewish veterans of the attack on Tantura sued him for libel, and several Jewish witnesses recanted.

Katz had breached the taboo of the ethnic cleansing that gave birth to Israel and which the Palestinians mourn as Nakba - the catastrophe. Without waiting for the case to come to court, the university struck Katz's name from its honour roll. Whispered to be a traitor, and under pressure from his family and friends, Katz, a devout Zionist who lived on a kibbutz, apologised. Twelve hours later, he retracted his apology.