Israel says it will use force if needed to prevent a ship chartered by the Libyan Gadaffi Foundation from breaking a blockade on Gaza.
The foundation has 2000 tonnes of food and medicine onboard a freighter which left a Greek port on Saturday. The Amalthea could reach Gaza later this week.
The ABC reports Israel is demanding the crew divert to its southern port of Ashdod, or to Egypt.
Israel stopped an international aid flotilla in international waters on 31 May. Nine Turks were killed, provoking a major diplomatic crisis with Turkey.
Israeli minister Daniel Hershkovitz has made it clear the Amalthea will not be allowed in.
"Israel hasn't changed its policy and its policy is very clear. No ships will allow to arrive at Gaza," he said.
Instead, Israel has offered to transfer the aid itself after inspection at Ashdod, just north of Gaza.
