PALERMO, Sicily (CN) - In an action deemed illegal, Israeli special forces early Monday detained a British-flagged yacht carrying 12 activists, including Swedish climate activist Greta Thunberg and a French-Palestinian European Parliament member, that left Sicily on June 1 intending to challenge Israel's blockade of humanitarian aid into the Gaza Strip.

The high-profile incident in the middle of the Mediterranean Sea drew attention to the humanitarian catastrophe unfolding in Gaza. It also underscored Israel's disregard for international law because the boat was sailing legally on the high seas when it was boarded and seized, experts said.

At 3 a.m. Monday, Israeli forces stopped the Madleen yacht and took over the boat, as seen on video provided by the Freedom Flotilla Coalition, a group challenging Israel's Gaza blockade. The group's vessel was about 120 miles west of Gaza when it was boarded. It was carrying baby formula, food and medical supplies.

"Israel has no legal authority to detain international volunteers aboard the Madleen," said Huwaida Arraf, a Freedom Flotilla organizer and lawyer, in a statement. "These volunteers are not subject to Israeli jurisdiction and cannot be criminalized for delivering aid or challenging an illegal blockade - their detention is arbitrary, unlawful, and must end immediately."

Rima Hassan, a European Parliament member from the far-left France Unbowed party, was among the activists on the Madleen. Hassan, 33, was born in a Palestinian refugee camp in Syria and arrived in France when she was nine.

"The idea was to bring both bring physical humanitarian aid to Gaza, but probably more important, given the small size of this ship, it's more important to bring international attention for a humanitarian disaster that's happening on the ground," said Manus Carlisle, a spokesperson for the Left, a group in the European Parliament that includes Hassan. He spoke to Courthouse News by telephone.

Israel said the vessel and activists were taken to the port of Ashdod, a major commercial port in southern Israel, not far from Gaza. They were expected to be deported after arriving in Israel.

"The 'selfie yacht' carrying Greta Thunberg and the other so-called 'celebrities' is continuing its journey toward an Israeli port," Israel's foreign ministry wrote on social media. "Upon arrival, arrangements will be made for their return to their respective home countries."

By late Monday, the foreign ministry said the group had arrived in Ashdod and was undergoing medical examinations "to ensure they are in good health."

Israeli Defense Minister Israel Katz said he ordered the army to force the activists to watch "the horror videos" of the Oct. 7, 2023, attack by Hamas on Israel. He accused Thunberg of being an "anti-semite" and the other activists of being "Hamas supporters."

Monday's incident comes just over a month after Israel was accused of attacking a Freedom Flotilla Coalition with drones off the coast of Malta. That attack took place about 14 nautical miles off the coast of Malta in international waters and caused a large fire.

"It seems like they can kind of get away with anything they want," Carlisle said. "It's quite incredible to us that a country can bomb essentially commercial or humanitarian vessels in the Mediterranean without our president of the [European] parliament, who's Maltese, saying anything about it or the president of the commission saying anything about it."

He was referring to European Parliament President Roberta Metsola and European Commission President Ursula von der Leyen.

In 2010, Israeli commandos attacked six humanitarian vessels, dubbed the "Gaza Freedom Flotilla," as they approached Gaza intending to break a naval blockade imposed by Israel. That Israeli attack led to the deaths of nine activists and left about 30 others wounded.

Seline Trevisanut, an expert on the law of the seas at Utrecht University, said it appeared Israel violated international law by detaining the Madleen.

"The location where the boarding happens is beyond the jurisdiction of Israel," she said in a telephone interview. "It was technically in the high seas where there is freedom of navigation."

International law allows vessels to be stopped and possibly boarded on the high seas only on specific grounds, such as piracy, sailing without a flag, transporting drugs, weapons of mass destruction and slaves.

"You have some legal ground, but they need to be explicit and authorized by international law, either in the form of a treaty or in the form of a U.N. Security Council resolution," she said.

But she said the boarding and seizure of the Madleen appeared unlawful.

"The vessel is, if I'm not mistaken, flagged in the U.K., so it had the possibility to enjoy the freedom of navigation," she said. "The boarding is questionable and could be considered as illegal."

In theory, she said Israel's actions could be contested by the United Kingdom because the vessel was sailing under its authority. She said the national governments of those aboard the vessel could also take legal action against Israel. Also, Thunberg and her fellow activists could try to challenge their detention in Israeli courts, she said.

On Monday, reaction from European leaders was cautious. Until very recently, the European Union and European governments have been largely silent about Israel's onslaught against Palestinians.

France called on Israel to return the six French nationals aboard the Madleen "as soon as possible." Sweden's foreign ministry said it was closely monitoring the situation, but it did not post any statements on social media about the incident.

Spain, meanwhile, summoned Israel's charge d'affaires in Spain. Spain is among the only EU states to criticize Israel.

Carlisle, the Left spokesperson, said the response from European leaders on Monday was disappointing but keeping with Europe's stance on Israel ever since it began its onslaught on Gaza following the Oct. 7 attack by Hamas.

"It's easier to talk about the lack of reaction, to be honest," he said.

Still, with the humanitarian crisis growing more catastrophic in Gaza, Israel's allies in Europe have begun to speak out in recent weeks and demand that Israel lift its blockade of aid.

"We've had plenty of statements from people like Ursula von der Leyen and other European leaders, but so far no actual action," Carlisle said.

He said the Left was the only group in the European Parliament "calling this a genocide following the lead of groups like Amnesty International and Human Rights Watch."

He said frustration is growing.

"The parliament has passed a number of resolutions over the past few months, and they have gotten steadily more proactive," he said. "They've gotten steadily more desperate, one might say, in calling for Israel to stop; to improve the humanitarian situation first of all and stop the onslaught on the ground."

In a statement, Brazil urged Israel to release the Madleen's passengers, among whom was Thiago Avila, a Brazilian citizen.

"Recalling the principle of freedom of navigation in international waters, Brazil urges the Israeli government to release the detained crew members," the Brazilian foreign ministry said.

Brazil called on Israel "to immediately lift all restrictions on the entry of humanitarian aid into Palestinian territory, in accordance with its obligations as an occupying power."

Courthouse News reporter Cain Burdeau is based in the European Union.

Source: Courthouse News Service