Israel has warned that journalists found onboard a planned flotilla to the Gaza Strip will be banned from the country for 10 years and face other sanctions.

The head of the government press office said in a letter to journalists Sunday that the flotilla is being organized by Western and Islamic extremists, and that those taking part would be in violation of Israeli law.

The Foreign Press Association condemned the warning, saying it raises “serious questions” about Israel's commitment to press freedom.

Organizers say the flotilla of as many as 10 ships will carry humanitarian goods and hundreds of pro-Palestinian activists to Gaza. It is not clear when the ships will set sail, but organizers have said it could begin this week.

The effort will also commemorate the flotilla effort broken up by Israel in May of last year.

Israeli commandos killed nine Turkish activists, including one who also had U.S. citizenship, when the Israeli forces boarded a Turkish vessel that was part of a flotilla trying to break the Israeli blockade of Gaza.