Military elements monitoring the Gaza flotilla said that radical elements taking part in the sail have said they were planning "surprises for the IDF" and plan to kill many soldiers.
The information suggests that radicals are planning to equip some of the vessels with bags containing chemicals, possibly sulfur, which they will use against soldiers who may try to take over the ships.
It has recently been estimated that only eight ships will take part in the sail, instead of 15. Some 500 activists are expected to board the vessels, half the original estimated number. They will include several prominent Hamas members such as Amin Abu Rashad, who heads a charity in Holland and Mohammed Ahmed Hanoun.
Meanwhile, some activists claim the ships have been tampered with. "They sabotaged the ship. They cut the propeller's hinge below water while the ship was in the port of Piraeus in Athens," Israeli expat Dror Feiler told Ynet. He added that the malfunction is currently being fixed.
"It's awful. Not only is the blockade being exported to Greek waters and the Greek government being pressured to stop the departure, now we're also being attacked in Greek territorial waters, thousands of kilometers from Israel's shores."
Preparing to set sail in Greece
Feiler also criticized the Greek government. "The Greek government is trying to mount any bureaucratic obstacle to prevent or postpone the ships' departure. There are unnecessary checks, approvals being delayed and extra papers being required.
"Israel needs to know that no matter what they do we are determined to set sail and break the illegal siege and open a naval corridor to Gaza."
The US, on its part, continues to issue warnings to citizens and journalists against participating in the flotilla. State Department spokeswoman Victoria Noland said Monday that the US is concerned with the situation which could prove provocative and dangerous.
She added there were other ways to transfer supplies to Gaza, stating that the mechanism created by Egypt and Israel was sufficient for such efforts.
Noland urged restraint and expressed hope things won't turn out as they did last year. She reiterated the US's support of Israel's right to defend itself against arms smugglings.
Boaz Fyler, Attila Somfalvi and Yitzhak Benhorin contributed to this report