Israel said that dozens of activists intercepted by the Israeli military from a Gaza-bound aid flotilla in international waters off Crete, which include seven Irish citizens, would be taken to Greek shores where they would disembark.
Israel's foreign ministry earlier said around 175 activists had been taken off more than 20 boats and were heading back to Israel.
The intercepted vessels form part of the latest flotilla of pro-Palestinian activists seeking to break Israel's blockade on Gaza.
Israeli Foreign Minister Gideon Saar wrote on X, thanking the Greek government "for its willingness to receive the flotilla participants."
The organisers of the flotilla said Israeli forces intercepted the aid ships in international waters near Greece, decrying the move as an "escalation of Israel's impunity".
The sister of President Catherine Connolly, Margaret Connolly, is on board one of the vessels that is part of the flotilla.
It is understood that the ship she is on was not intercepted by Israeli forces and is still sailing towards Greece.
The Department of Foreign Affairs has said it is providing consular assistance to impacted Irish citizens.
In a statement, the department added that it is "actively monitoring the situation regarding the Global Sumud Flotilla and are engaging with the relevant authorities".
Caoimhe Butterly, who is an Irish activist on board an independent observer vessel following the flotillas, said the ages of those detained range from mid-20s to a mariner who is 76 years old.
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Speaking on RTÉ's Morning Ireland, she said she has received no updates.
However, she said one of the main vessels in the military action was a large naval vessel, and perhaps people were transferred to that, but they could still be on their sailboats.
"We were over 1,000 miles from Gazan territory or waters, so although those on board had prepared themselves for the possibility of illegal interception it was certainly not something we were expecting to begin, so close to Greece, to Crete and in clear violation of international law, yet again."
Ms Butterly was within the fleet when the interceptions happened before creating some distance.
However, she said based on what she could observe and radio communications, the interception began with Israeli commandos going "boat by boat, taking control of the boats and placing those on board under detention which, under international law, constitutes illegal detention in waters that are not under the jurisdiction of the Israeli army".
She added that this could translate to a possibility of illegal kidnapping on the high seas.
A second flotilla carrying humanitarian aid to Palestinians in Gaza sailed from the Spanish port of Barcelona on 12 April, aiming to try to break the Israeli blockade.
Watch: Irish woman describes interception of Gaza aid flotilla by Israel off Greece
The vessels were seized by Israel hundreds of miles from Gaza, said the organisers, Global Sumud Flotilla.
"This is piracy," the group said in a statement.
No state had the right to claim, police, or occupy international waters, but Israel had done that, extending its control outward to occupy the Mediterranean Sea off the coast of Europe, it added.
"This is the unlawful seizure of human beings on the open sea near Crete, an assertion that Israel can operate with total impunity, far beyond its own borders, with no consequences."
Israel controls all entry points to Gaza and has been accused by the United Nations and foreign NGOs of strangling the flow of goods into the territory, causing shortages since the start of its war in Gaza in October 2023.
Israel's UN envoy Danny Danon said the flotilla "was stopped before reaching our area".
Israel's military halted a previous flotilla assembled by the same organisation last October in an attempt to reach blockaded Gaza, arresting more than 450 participants.
Palestinians and international aid bodies say supplies reaching the territory are insufficient, despite a ceasefire reached in October that included guarantees of increased aid.
The wife of an Irish man taken from the flotilla by Israeli forces last night said she was shocked Israeli forces had entered European waters.
Another Irish activist on board the Gaza aid flotilla says the mood remains 'defiant' following last night's Israeli intervention in international waters.
Mikey Cullen, a teacher and poet from Dublin, said his boat and others in the flotilla were still continuing towards the Strip.
"We're defiant and more resolute than ever," he said.
Watch: Irish activist on Gaza aid flotilla says mood 'defiant'
'They're nowhere near Israel,' says wife of detained flotilla member
Rachel McNicholl said her husband, Fiacc O Brolchain, is a very experienced seafarer who trained crews and volunteered to skipper the first leg of the route.
"The plan was always that he would come home from Greece," she said.
"He's 74 and he didn't really think it would be a good idea to end up in an Israeli jail."
Speaking at a rally in support of the flotilla at Leinster House, Ms McNicholl said: "I don't know whether he's been taken to Israel, I don't know what's happening."
She said she was very worried for her husband's welfare but also "shocked" Israel forces came so far north.
The boats were about 45 nautical miles west of Crete and around 800 nautical miles from Israel, she said.
"They're nowhere near Israel, and yet, the Israeli military went in with drones and then started boarding boats, wrecking navigation systems, and some people have just disappeared.
Ms McNicholl said she believed this was the first time Israel had gone so far into European waters.
"They knew it was a risky kind of operation," she said. "But as far as I was concerned, as far as he was concerned, there would be very little risk between Sicily and Greece.
"They're nowhere near Israel. They're nowhere near Gaza.
"So, and I hope that the Israeli government doesn't get away with this."
She said the Department of Foreign Affairs had been in touch and were working out where the Irish citizens are.
Spain 'energetically condemns' Israel's interception of Gaza-bound flotilla
Spain has said it "energetically condemns" the seizure by Israeli forces of the Gaza-bound aid flotilla carrying Spanish nationals in international waters off Greece.
Madrid has summoned Israel's charge d'affaires in Spain to convey its protest over the detention of the vessels, the foreign ministry added in a statement.
Spanish diplomatic staff in Israel are in contact with the organisers of the flotilla and Foreign Minister Jose Manuel Albares has spoken with his counterparts who also have nationals on board, the statement said.
Meanwhile, the World Health Organization has said that even during armed conflicts, states are obligated under international humanitarian law to ensure that people are able to reach medical care in safety.
"This is a mission that aims to open a humanitarian corridor so the aid delivery organisations can arrive," Saif Abukeshek, a Palestinian activist and member of the flotilla's organising committee, said.
Activists on last year's flotilla said they were subjected to inhumane conditions during their detention by Israeli forces - an allegation that was rejected by an Israeli foreign ministry spokesperson.
Additional reporting: PA
