The Foreign Press Association has accused the Israeli government of using "threats and intimidation" to stop media coverage of a 10-ship flotilla due to sail to the Gaza Strip this week.
The ships are sailing to protest against Israeli restrictions on Gaza and to commemorate last year's flotilla, which was intercepted by the Israeli navy, who killed nine of the Turkish participants.
Israel has restricted the supply of goods and the movement of individuals in Gaza since Hamas took control in 2007.
Two of the ships, the Tahrir and the Audacity of Hope, are docked in Athens, where the harbourmaster has banned the latter from leaving port until its seaworthiness is established.
Some of the other ships, including the Irish ship Saoirse, have already set sail from European ports. The ships are expected to meet in the Mediterranean before approaching Gaza later this week. The flotilla is expected to carry up to 500 passengers.
A Dutch-Italian boat will carry three members of the European parliament and one member of the Israeli parliament. Passengers on the Audacity of Hope include the author Alice Walker and Hedy Epstein, an 87-year-old Holocaust survivor. Passengers have been undergoing training in non-violent resistance techniques and instruction in what to expect if Israeli soldiers board their ship. They have also been provided with T-shirts with the message "Unarmed Civilian".
Israel has been engaged in a diplomatic campaign to prevent the flotilla from setting sail. Hillary Clinton, the US secretary of state, said last week that the flotilla was not "useful" and consular officials tried to persuade US nationals in Athens not to join the flotilla.
On Sunday Israel warned journalists, who will make up a minority of the passengers, not to travel with the flotilla. In a letter to editors, Oren Helman, the director of the government press office, wrote that the flotilla had been organised by western and Islamist extremists: "The flotilla intends to knowingly violate the blockade that has been declared legally and is in accordance with all treaties and international law."
He said journalists who participated in the flotilla would be breaking Israeli law and would be banned from Israel for 10 years, as well as facing confiscation of equipment and other measures.
The Foreign Press Association, which represents the international media in Israel, said the threat to punish journalists covering the Gaza flotilla raised serious questions about Israel's commitment to freedom of the press. "Journalists covering a legitimate news event should be allowed to do their jobs without threats and intimidation. We urge the government to reverse its decision immediately," it said.
