The Israeli military has intercepted several ships from the flotilla of vessels carrying humanitarian aid to the besieged Gaza Strip, detaining many of the activists on board.

At least three ships from the Global Sumud Flotilla, made up of 44 vessels and some 500 activists, were intercepted approximately 70 nautical miles (130km) from the coast of Gaza, according to organisers.

Israel’s Ministry of Foreign Affairs said in a post on X on Wednesday that “several vessels” of the flotilla were “safely stopped and their passengers are being transferred to an Israeli port”.

It wrote that Swedish activist Greta Thunberg, who had been on board the lead ship Alma, “and her friends are safe and healthy”. The ministry also shared a video showing Thunberg.

So far, at least six ships have been intercepted by the Israeli navy, according to the activist group. The names of the vessels are Deir Yassin/Mali, Huga, Spectre, Adara, Alma and Sirius.

Several ships were targeted by acts of “active aggression”, it said. “Florida vessel has been deliberately rammed at sea. Yulara, Meteque and others have been targeted with water cannons,” it said on Telegram.

All passengers on board were unharmed, it added. Before being intercepted, the vessels had succeeded in sailing beyond the point where the Madleen Flotilla was intercepted by Israeli forces earlier this year.

Before the interceptions began, the activists warned the Israeli military had cut off their connection by disabling their devices, which affected their cameras, their livestreams and communications systems that allowed the ships to relay messages to the world.

The Global Sumud Flotilla’s official channels denounced Israel’s actions in a statement, saying the mission’s vessels were being “illegally intercepted”.

“People of conscience have been abducted,” it said on X. “The flotilla broke no laws. What is illegal is Israel’s genocide, Israel’s illegal blockade of Gaza, and Israel’s use of starvation as a weapon.”

The statement urged supporters to pressure governments to act, writing: “Demand your government cut ties with Israel.”

United States citizen and activist Leila Hegazy, who is on one of the vessels, posted a prerecorded message on social media stating that her sharing the video means she has been “kidnapped by the Israeli occupation forces and brought to Israel against [her] will”.

“I ask you all to pressure the United States government to end its complicity in the genocide of the Palestinian people in Gaza and also to ensure the safe return of every humanitarian on this mission,” she said.

Hassan Jabareen, director of the legal centre Adalah, which has represented flotilla activists in the past, told Al Jazeera that “this time, we do not know what Israel will do”.

The activists could be deported within 72 hours, according to the law, or brought to court within 96 hours. He added that some activists could be arrested but noted that Israel usually opts for immediate release.

“If they arrest and detain them, it can lead to a losing situation, because media coverage will continue as long as they are in custody,” Jabareen said.

Israel’s ambassador to the United Nations, Danny Danon, said the activists would be deported once the Jewish holiday of Yom Kippur concludes on Thursday.

Turkiye’s Ministry of Foreign Affairs condemned Israel’s interception of the boats, denouncing it as an “act of terrorism” and a severe breach of international law. In a statement, the ministry said it was taking initiatives to ensure the immediate release of Turkish citizens and other passengers detained by the Israeli forces.

Italy’s Foreign Minister Antonio Tajani said the Israeli operation was expected to take two to three hours. He told state TV Rai that the boats would be towed to Israel’s port of Ashdod and the activists would be deported in the coming days. He also said Israeli forces have been told “not to use violence”.

As news of the interceptions circulated on social media, protests broke out across several major world cities, including Athens, Rome, Berlin, Brussels, Tunis and Ankara. Italy’s largest union called a general strike for Friday in protest over the treatment of the Sumud Flotilla.