As hoards of journalists and foreign military attaches gathered on the quayside at a naval base in the southern resort town of Eilat, the weapons seized during last week's Red Sea raid were laid out in full view.
On board the Panamanian-flagged Klos-C, troops found 40 long-range M-302 rockets, 181 122mm mortar shells and approximately 400,000 7.62-calibre rounds.
Also on display were sacks of cement under which the weapons were hidden. On the sacks, written in English, were the names "Fars and Khozestan Cement Co" and "Hormozgan Cement Company" - both of them the names of firms based in Iran.
Israeli investigators do not believe the crew was aware of the vessel's true cargo.
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Israel has said it has "solid and incriminating evidence" that Iran planned and executed the shipment, with the aim of sending the arms to Palestinian militants in Gaza.
But so far, it has not made such evidence public, with Netanyahu suggesting the proof would be shown on Monday.
Defence Minister Moshe Yaalon and navy chief Vice Admiral Ram Rutberg will also speak at the news conference.
Netanyahu yesterday accused Tehran of "brazenly lying" about its ties to the weapons cache, which analysts suggested were being sent to Islamic Jihad, a militant group operating in the Hamas-run Gaza Strip.