The ship set sail from the Lebanese port of Tripoli Tuesday in a bid to defy Israel's blockade of Gaza. Reporters from Arab TV stations Al-Jadeed and Al-Jazeera who were on the vessel said the Israelis fired at the ship before boarding it and beating those on board.
Organizers said a total of 18 people were on board. Among them was 86-year-old Greek Catholic priest Hillarion Capucci, who while serving as an archbishop in Jerusalem was convicted in 1974 by an Israeli court for using his diplomatic status to smuggle arms to Palestinian militants. The Syrian-born Capucci was jailed but released three years later at the intervention of the Vatican and deported.
The organizers said four journalists, a Muslim cleric and a lawyer - all Lebanese citizens - as well as a Palestinian Muslim cleric and a British activist were also on board. They had no information on the nationality of the nine crew members.
The Israeli military said that those on board the ship, the Togolese-flagged "Tali" would be handed over to Israeli police and the aid would be transferred to Gaza by land.
Israel has kept Gaza's cargo crossings largely closed since the Hamas militant group seized control of the coastal strip in June 2007.
Israel says the blockade is a response to repeated Hamas rocket attacks on southern Israel and is necessary to keep arms from reaching Hamas. Since Israel ended a three-week military offensive in Gaza, Hamas has been trying to secure a reopening of the border crossings as part of a long-term cease-fire.
The army said the delivery had not been cleared by Israeli authorities, who have turned back similar attempts to reach Gaza by sea.
The military said that a naval patrol spoke by radio to the Tali, told its skipper that it would not be allowed to enter Gaza and the two sides agreed that the vessel would instead sail to the Egyptian port of El-Arish.
But on Thursday morning, the ship tried to double back and slip past the navy, Israel said, raising concerns that it might be trying to smuggle arms into Gaza.
"As a result of the actions taken by the boat crew, an Israel Navy force intercepted, boarded, and took control of the cargo boat, directing it toward (the port) of Ashdod, Israel," the statement said. "No gunshots were fired on board during the boarding and capturing of the cargo boat."