A Swedish ship due to join an upcoming Gaza-bound aid flotilla has been sabotaged in the Greek port of Piraeus, organizers say.
In a statement, they said, "hostile divers had destroyed the propeller house and cut the propeller shaft" of the vessel Juliano on Monday .
The ship is part of the 10-vessel Freedom Flotilla II that is expected to set sail from Greece and elsewhere for the Gaza Strip in the coming days in a bid to break Israel's blockade of the Palestinian territory.
About 350 pro-Palestinian activists from 22 countries are likely to participate.
Israel insists the latest flotilla is a "dangerous provocation" and has vowed to intercept it.
Organizers of the flotilla, however, remain defiant and said the Juliano would be ready to sail within one or two days after being repaired. They said they had documented the sabotage with their own camera-equipped divers.
"We are sad that people are doing such things but we are determined to continue to Gaza," Dror Feiler, one of the organizers, told Al Jazeera from aboard the Juliano.
"We will not be frightened by Israel, and we are going to continue. Our friends from all around the world are with us, and we are all going to Gaza."
Mattias Gardell, a spokesperson for Ship to Gaza Sweden, also condemned the act of sabotage.
"It's one thing for a foreign power to press the Greek government to delay our voyage with red tape. It is quite another thing for enemy agents to operate on Greek territory.
"It is high time for the international community to put their foot down and say: Enough!"
Israeli newspaper Haaretz quoted senior Israeli officials as saying that "radical elements" among the flotilla activists had stated an intention to "spill the blood of Israeli soldiers."
According to Tel Aviv daily Yedioth Aharonoth, military sources said participants of the flotilla were planning to pour chemicals, such as sulfur, on Israeli soldiers.