Updated

Israel's navy intercepted a vessel attempting to breach a naval blockade of Gaza early Monday and was redirecting it to an Israeli port, the military and the activists said.

The military said that after exhausting all diplomatic efforts the government ordered it to block the Swedish vessel. Israeli naval forces visited the Marianne ship and searched it in international waters without needing to use any force, the military said. The ship was carrying about 20 activists, including Israeli Arab lawmaker Basel Ghattas and former Tunisian President Moncef Marzouki.

The Freedom Flotilla group posted a photo on Twitter apparently showing a group of its activists onboard a ship. It said in the post that Israeli forces intercepted the Marianne and it was currently en route to Ashdod port. Calls to Ghattas and his assistant rang unanswered.

The activists have said previously they were trying to draw attention to the blockade and would not resist if stopped by the navy.

A 2010 raid against a Gaza-bound flotilla encountered violent resistance and nine Turkish pro-Palestinian activists were killed. It sparked international criticism of Israel and delivered a serious blow to its previously close ties with Turkey.

Israel and Egypt have maintained a blockade of Gaza since Hamas militants took power in 2007. Islamic militants in the coastal strip have fired thousands of rockets toward Israel and have repeatedly tried to smuggle in arms through the sea.

Prime Minister Benjamin Netanyahu said the naval blockade of Gaza is in accordance with international law and has been endorsed by a United Nations committee.

"This flotilla is nothing but a demonstration of hypocrisy and lies that is only assisting the Hamas terrorist organization and ignores all of the horrors in our region," he said after the ship was redirected. "We are not prepared to accept the entry of war material to the terrorist organizations in Gaza as has been done by sea in the past."

Israel says there is no siege on Gaza and that Israel transfers about 800 trucks a day into Gaza and recently brought in more than 1.6 million tons of goods.