JERUSALEM — Israel set up three massive white tents at its main southern seaport on Thursday to hold hundreds of pro-Palestinian activists who hope to breach Israel's 3-year blockade of the Gaza Strip.

The activists are headed toward Gaza's waters on board a flotilla carrying 10,000 tons of supplies. Israel says it won't let the eight boats reach Gaza's shores, and that it will deport or imprison the activists aboard.

The military said it would divert the boats to the Israeli port at Ashdod, where the activists will be taken into the tents for identification and medical attention.

Officials said 40 buses will be on hand to ferry them to Israel's international airport for deportation or to a nearby prison if they refuse to be deported voluntarily.

"We want to do this as quick and efficiently as possible," said Maya Kadosh, a Foreign Ministry spokeswoman.

Israeli authorities said they will make every effort to avoid using force, but they were prepared for a military confrontation if necessary.

Speaking by satellite phone to The Associated Press from his ship, "Free Mediterranean," flotilla organizer Dror Feiler was defiant. "We are on a humanitarian and solidarity action, we intend to continue it until we reach our goal and will not be stopped," he said.

Feiler, 68, a musician who renounced his Israeli citizenship, said he brought a saxophone with him and will greet Israeli sailors boarding his boat with music "from the time when Jews didn't have armies and police to harass freedom fighters, when Jews were victims, and were standing at the forefront of the fight for the dignity of people."

Feiler said there are four passenger boats and four cargo ships in the flotilla. He said his left the Greek island of Rhodes on Thursday morning. Others embarked from various European ports, organizers said.

Israel's navy chief, Vice Adm. Eliezer Marum, has overseen a series of drills in recent days simulating the boarding of the ships and their transfer to shore, the military said. Authorities refused to provide further details, including how large a force they planned to deploy.

As for the supplies on board, Israeli authorities said they would undergo a security check, and then transfer them to U.N. agencies to be distributed in Gaza. Israel said the activists should have chosen this option in the first place if they wished to get the materials to Gaza.

"If they were really interested in the well-being of the people of Gaza, they would have accepted the offers of Egypt or Israel to transfer humanitarian aid to the people of Gaza," said Israeli government spokesman Mark Regev. "Instead they have chosen a cheap political stunt."

Israel imposed its blockade on Gaza after Hamas militants violently seized control of the coastal area in June 2007. The situation worsened following an Israeli military offensive meant to stop Hamas rocket attacks early last year.

While aid shipments and a bustling smuggling trade along the Egyptian border have managed to get most basic items into Gaza, the blockade has made it impossible to repair damage to thousands of homes that were damaged or destroyed in the Israeli offensive.

Israeli authorities reject allegations that a humanitarian disaster is brewing in Gaza.

"There is no shortage of fuel, there is no shortage of medication, there is no shortage of any necessities in the Gaza Strip," said military spokeswoman Avital Liebovitch. "There is no humanitarian crisis in Gaza. The situation is stable."