The pro-Palestinian activists who hope to breach the blockade of the Gaza Strip have rejected a Greek offer to take the cargo of the flotilla to Gaza for them.
A group on the US ship The Audacity of Hope also announced that they would undertake a hunger strike in protest at the Greek government's decision to stop the flotilla from sailing from there. The captain of their ship was taken into custody by Greek police.
The Turkish government also moved to stop boats sailing to Gaza.
Israel agreed to allow the Greek navy to ship what was on board, provided the cargo could be checked for weapons.
But one of the activists said they would not allow it . "We want to break the siege and the flotilla is not about expanding the drip of humanitarian aid to Gaza," she said.
The activists have also suggested they may attempt to flout the Greek ban. Israel's Defence Minister Ehud Barak said that while the developments with the flotilla were positive, Israel "obviously still need[ed] to prepare for the possibility that flotillas [would] arrive."
Greece's Prime Minister George Papandreou was praised for taking action to stop the flotilla by the New York-based Anti-Defamation League. Abraham Foxman, ADL national director, said he had acted responsibly and set an "example for the entire international community".
He added: "Greece's actions to stop these ships from using Greek ports as a launching point will help prevent the public confrontation with Israeli naval authorities these activists are seeking."