text: Police say they are investigating allegations of a secret price-fixing arrangement by companies who organise the trips for students.
  Investigators have raided the homes of executives and frozen bank accounts.
  At least six travel agencies are accused of violating competition rules.
  They are suspected of colluding on prices before responding to an education ministry tender to take students to Holocaust memorials.
  When the Israeli education ministry approached a number of different companies, it received identical quotes.
  Reports say the alleged collusion was aimed at artificially inflating prices.
  Drone video shows the Auschwitz-Birkenau concentration camp
  Why did ordinary people commit atrocities in the Holocaust?
  The Holocaust year by year
  Thousands of Israeli high school students travel to memorials at World War Two death camps every year. A trip can cost several thousand shekels per student (1,000 shekels is worth Â£177), according to reports in Israeli media.
  The BBC's Kevin Connolly, in Jerusalem, says that for many Israeli high school students a visit to the site of the Nazi death camps in southern Poland is a rite of passage, which gives them a direct sense of connection to the Holocaust - the defining tragedy of modern Jewish history.
  If the allegations are proved to be true, our correspondent adds, there will be shock in Israel that a form of tourism that is viewed with great solemnity may have been the subject of illegal business practices.
  Some six million Jews were murdered by the Nazis during the Holocaust, mainly in death camps in occupied Poland. More than a million people, mostly Jews, were killed in Auschwitz alone.
target: Nine executives at Israeli travel agencies have been arrested on suspicion of fixing the price of high school students' trips to former Nazi death camps, including Auschwitz.