Israel's navy took over a Swedish vessel attempting to breach a naval blockade of the Gaza Strip early on Monday and brought it to an Israeli port. It said the foreign activists would be questioned before they are sent back to their home countries.
The military said that after exhausting all diplomatic efforts, the government ordered it to block the vessel. Israeli naval forces boarded the Marianne 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. Three other ships that were part of the original flotilla reversed course before encountering the Israeli navy.
The Israeli military issued a statement Monday night saying vessel had arrived at the Ashdod port. "The vessel and crew members are now being transferred to the appropriate authorities for immigration and deportation processing," it said.
Interior Ministry spokeswoman Sabine Haddad said it could take a few days to deport them, depending on available flights.
The Freedom Flotilla group posted a photo on Twitter apparently showing a group of its activists onboard a ship.
Petros Stergiou, a member of flotilla's media team in Athens, said the group would continue its acts of protest until the blockade of Gaza was lifted.
"Once again, the Israeli state commits an act of state piracy in the Mediterranean Sea," he said. "The government continues this policy of non-tolerance, which means that it will continue to enforce the collective punishment against the 1.8 million people in Gaza."
A 2010 Israeli raid against a Gaza-bound flotilla left nine Turkish pro-Palestinian activists dead. It sparked international criticism of Israel and delivered a serious blow to its previously close ties with Turkey.
Israel has 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 by sea. Israel says the blockade is needed to prevent the militants from stockpiling weapons.
While Israel insists there is no siege, there are severe restrictions on Palestinian movement and trade, with virtually no exports. The international community, including the United Nations, has repeatedly called for an end to the blockade.
Prime Minister Benjamin Netanyahu said the naval blockade of Gaza is in accordance with international law.
"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. "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 it transfers about 800 trucks a day into Gaza and recently brought in more than 1.6 million tons of goods. It says it assists in hundreds of humanitarian projects, through international organizations, including the building of hospitals and clinics.
Reconstruction efforts in Gaza have nevertheless made little progress since last summer's devastating war. Tens of thousands are displaced within the narrow coastal territory and others are still living in damaged apartments.