There has been no contact with any people forcibly detained on an aid flotilla by Israeli forces in international waters yesterday, an Irish activist has said.
Dr Margaret Connolly, the sister of President Catherine Connolly, is among those on board.
The organisers of the flotilla said Israeli forces had intercepted 41 of their boats in the eastern Mediterranean, with ten vessels still sailing toward the enclave.
The closest vessel to Gaza, Sirius, was 145 nautical miles away, the group said.
Israel's foreign ministry had said on X that it "will not allow any breach of the lawful naval blockade on Gaza".
Watch: Irish activist sails on 'undeterred' after Israel intercepts more vessels in Gaza-bound flotilla
Activist Caoimhe Butterly, who had been on board an observer boat following the flotilla of aid vessels bound for Gaza, said there have not been any updates since the interception of vessels yesterday.
Speaking on RTÉ's Morning Ireland, she said: "Those on board, which constitute over 400 humanitarians, healthcare workers, social workers and people really from a wide diversity of walks of life, have all been now illegally abducted, and are being presently detained on a converted cargo prison ship."
Ms Butterly said there is no indication where those detained will be taken but it is likely that they will be brought to Ashdod Port in Israel, where they will be detained before deportation.
She added that it is unlikely that the presence of Dr Connolly will result in improved treatment for those detained.
"So one would hope that Margaret's presence brings a measure of safety to those around her, but I would say that Margaret Connolly was also very clear that her remit and her presence on board the flotilla, as well as being the President's sister, was also as a health care worker, and to try and kind of spotlight on the systematic targeting of Palestinian healthcare workers," Ms Butterly said.
She also said that 12 out of 15 Irish citizens have been detained since the flotilla left Barcelona five weeks ago.
Ms Butterly added that there are three Irish citizens on board the boats that remain en route towards Gaza, but it is anticipated that these vessels will be intercepted.
The flotilla posted videos from Dr Connolly and five others earlier today, which appear to have been recorded in advance of their detention.
Watch: President 'very worried' after sister detained by Israel on ship
In her video, Dr Connolly said: "If you are watching this video, it means I have been kidnapped from my boat in the flotilla by the Israeli occupying forces, and I'm now being held illegally in an Israeli prison.
"I am so proud to be taking part in this flotilla - it is the largest to date."
In an interview with TG4, President Catherine Connolly said that the incident happened in international waters.
"It's quite upsetting, and I'm very worried about her, and I'm also very concerned about her colleagues on board," she said.
Taoiseach Micheál Martin has said it is "wrong" and "unacceptable" that Irish citizens have been detained by Israeli forces.
He said the behaviour of Israel in international waters against the aid flotilla is "unacceptable" and that people have a right to protest and take part in a mission to highlight the "shocking" humanitarian issue in Gaza.
"In the first instance, what happened is absolutely unacceptable and is wrong," Mr Martin said ahead of Cabinet.
"We have condemned that as we have before where Israel intervenes in international waters and detains and essentially abducts people from the ships, and that’s unacceptable and the international rule of law has to apply."
He said the issue will be raised at EU level alongside issues pertaining to Gaza and the West Bank.
Israeli actions in breach of international law - Tánaiste
Meanwhile, Tánaiste Simon Harris said Israel's detention of Irish citizens is in breach of international law.
He also sympathised with President Connolly regarding her sister's detention.
Speaking this morning, he said: "My heart goes out to President Connolly and her family, and indeed all of the families of those detained.
"What Israel has done is, in my view, illegal. It is, in my view, in breach of international law, quite frankly, not even in my view, it is a breach of international law.
"You cannot take citizens of another country in international water and detain them. That is illegal.
"We don't need to try to suggest there's some sort of gray area here where there clearly is. It's actually quite black and white."
He said the Minister for Foreign Affairs and Trade, embassies in the region, including in Tel Aviv, are working very intensively on this.
Speaking in Ankara last night, Turkish President Recep Tayyip Erdoğan condemned the intervention against the "voyagers of hope" in the flotilla and called on the international community to act against Israel's actions.
Ships from the Global Sumud Flotilla had set sail for a third time on Thursday from southern Turkey.
The group said there were 426 people taking part in the 54-vessel flotilla from 39 countries.
Israel's foreign ministry has called on "all participants in this provocation to change course and turn back immediately".
