The Freedom Flotilla Coalition (FFC), which launched the ship to draw international attention to the looming famine in besieged Gaza, said it was captured at about 4:02am (01:02 GMT) on Monday, about 200km (120 miles) from Gaza, arriving at Ashdod as night fell.
Earlier, the coalition released a video from the vessel, which left Sicily on June 1, showing the activists – among whom are climate campaigner Greta Thunberg and French member of the European Parliament Rima Hassan – with their hands up as Israeli forces boarded the vessel and “kidnapped” them.
Adalah, a Palestinian legal centre representing the activists, announced they were expected to be held at a detention facility before being deported.
It added that Israel had “no legal authority” to take over the ship, which was in international waters, heading not to Israel but to the “territorial waters of the State of Palestine”.
The arrests of the 12 “unarmed activists” amounted to “a serious breach of international law”, it noted in a statement.
Huwaida Arraf, an FFC organiser, told Al Jazeera there had been no contact with the activists since they had been detained in the early hours of Monday.
“We have lawyers on standby who are going to demand they have access to them tonight – as soon as possible,” she said.
The Madleen, she noted, was sailing under a United Kingdom flag when it was forcibly seized by Israeli commandos.
“So Israel went into international waters and attacked sovereign UK territory, which is blatantly unlawful. And we expect strong condemnation, which we have not yet heard from the United Kingdom,” she added.
Francesca Albanese, the United Nations special rapporteur for the occupied Palestinian territory, stated, “Israel has absolutely no authority to intercept and stop a boat like this, which carries humanitarian aid, and more than everything else, humanity, to the people of Gaza.”
Israel’s Ministry of Foreign Affairs portrayed the voyage as a public relations stunt, saying in a post on X that “the ‘selfie yacht’ of the ‘celebrities’ is safely making its way to the shores of Israel”.
It noted the passengers were “undergoing medical examinations to ensure they are in good health”, adding that all passengers were expected to return to their home countries.
Government spokesperson David Mencer reserved special scorn for 22-year-old Thunberg.
“Greta was not bringing aid, she was bringing herself. And she’s not here for Gaza, let’s be blunt about it. She’s here for Greta,” he stated.
In a prerecorded video message that was shared by the FFC, Thunberg said: “I urge all my friends, family and comrades to put pressure on the Swedish government to release me and the others as soon as possible.”
The Swedish Ministry for Foreign Affairs announced it was in contact with Israeli authorities.
“Should the need for consular support arise, the Embassy and the Ministry of Foreign Affairs will assess how we can best help the Swedish citizen/Greta Thunberg resolve her situation,” said a spokesperson in a written statement to the Reuters news agency.
United States President Donald Trump, who targeted Thunberg in 2019, dismissed her statement.
“I think Israel has enough problems without kidnapping Greta Thunberg,” he stressed.
Israeli Minister of Defence Israel Katz said the activists would be shown videos of atrocities committed during the October 7, 2023, Hamas-led attack on southern Israel.
Hamas condemned the seizure of the boat as “state terrorism” and stressed it saluted its activists.
