Those on board activists’ vessels include Greta Thunberg and Sinn Féin senator Chris AndrewsSimon Harris to convene meeting of senior officials this morning and is also due to speak with Ireland’s Ambassador to Israel

At least nine Irish citizens have been detained by the Israeli military after the international flotilla trying to deliver medicine and food to Gaza was intercepted overnight, organisers said.

Those detained were Sinn Féin Senator Chris Andrews, Catríona Graham, Louise Heaney, Sarah Clancy, Diarmuid Mac Dubhghlais, Cormac O’Daly, Colm Byrne, Thomas McCune and Tara O’Grady, according to the Global Sumud Flotilla.

Swedish climate campaigner Greta Thunberg is also among those who have been detained.

About 20 Israeli vessels were seen approaching the flotilla, multiple people on board said, as passengers put on life vests and braced for a takeover.

Organisers said that multiple vessels were “illegally intercepted and boarded by Israeli Occupation Forces in international waters”.

Taoiseach Micheal Martin said he was receiving ongoing briefings on the matter, adding that those on the flotilla posed no danger to anybody.

Speaking to reporters in Copenhagen, he said it was important that those on board were treated properly.

“It’s a humanitarian mission, no threat to anybody other than to highlight and also to bring humanitarian aid into the people of Gaza,” he said.

“And it underlines the absolute imperative of getting humanitarian aid into Gaza as quickly as possible under the auspices of the United Nations and the Red Crescent, as outlined in the peace proposals that emanated from the United States in consultation with the Arab states.”

Asked if it was a breach of international maritime law, Mr Martin replied: “If it happened in international waters, yes.”

Mr Martin said the Department of Foreign Affairs had consistently advised against people visiting the area “because of the obvious dangers”.

He added: “I think the the paramount consideration has to be the safety of all those on the flotilla.”

Mr Martin said he has been receiving briefings in relation to the interception and confirmed the Irish ambassador is in touch with the Israeli authorities.

“We will be providing consular assistance to those who have been detained,” he said.

“It is important they are treated properly, it’s a humanitarian mission.

“No threat to anybody other than to highlight and also to bring humanitarian aid to the people of Gaza and it underlines the absolute imperative of getting humanitarian aid into Gaza as quickly as possible under the auspices of the United Nations and the Red Crescent, as outlined in the peace proposals that emanated from the United States in consultation with the Arab states.”

Tánaiste Simon Harris will convene a meeting of senior officials this morning to discuss the evolving situation with Global Sumud Flotilla overnight. He is also due to speak with Ireland’s Ambassador to Israel.

“The overriding concern remains the welfare of those on board, including Irish citizens. Our latest understanding is that passengers will be transferred to an Israeli port for processing and that Ireland’s Embassy on the ground will liaise with local authorities and provide consular assistance,” he said.

“This is a peaceful mission to shine a light on a horrific humanitarian catastrophe. Ireland expects international law to be upheld and all those on board the flotilla to be treated in strict accordance with it.

The Tánaiste also reiterated his broader call for “progress on the peace efforts to stop the killings in Gaza, stop the famine and release the hostages”.

The Global Sumud Flotilla said that its communications were jammed before boarding of Israeli personnel began, which interfered with cameras that were providing live streams from various boats and communications between vessels.

The Israeli foreign ministry said in a statement that several vessels of the flotilla had been stopped and their passengers were being transferred to an Israeli port.

Greta Thunberg, the Swedish climate campaigner, and her friends are “safe and healthy”, the foreign ministry said in a post on X alongside a video that appeared to show Ms Thunberg with several masked and armed Israeli military personnel.

It is believed at least 20 Irish citizens overall – including Sinn Féin senator Chris Andrews, author Naoise Dolan and ­comedian Tadhg Hickey – are aboard the flotilla.

Tánaiste and Foreign Affairs Minister Simon Harris said last night: “I am keeping in close contact with my officials who are working on the ground and have also spoken with EU counterparts on the Global Sumud Flotilla.

“Tonight’s reports are very concerning. This is a peaceful mission to shine a light on a horrific humanitarian catastrophe. Ireland expects international law to be upheld and all those on board the flotilla to be treated in strict accordance with it.”

Shortly before 8pm Irish time, Mr Andrews wrote on X: “Israeli warship directly off my boat, the Spectre. Boarding is imminent and this will likely be my last post before I am kidnapped.”

There are 12 to 14 Israeli army vessels lined up in front of us

Mr Andrews was among a number of activists aboard the flotilla to post videos on social media.

“There are 12 to 14 Israeli army vessels lined up in front of us, and we should meet them in about an hour, around an hour,” Mr Andrews said in the video posted to his X account.

“So, this is a peaceful and non-violent humanitarian mission to open up a corridor into Gaza to get aid and food and supplies to the residents of Gaza.”

The Global Sumud Flotilla, which consists of more than 40 civilian boats carrying about 500 parliamentarians, lawyers and activists, was trying to break Israel’s blockade of Gaza, despite repeated warnings from Israel to turn back.

It was about 70 nautical miles off the war-ravaged Strip, inside a zone that Israel is policing to stop any boats approaching.

Israel’s foreign ministry earlier said the navy had warned the flotilla it was approaching an active combat zone and violating a lawful blockade, and asked it to change course.

The ministry said it reiterated the offer to transfer any aid peacefully through safe channels to Gaza.

The flotilla is the latest sea-borne attempt to break Israel’s blockade of Gaza, much of which has been turned into a wasteland by almost two years of war.

The flotilla had been hoping to arrive in Gaza on Thursdaythis morning.

This was the second time the flotilla was approached on Wednesyesterday. Before dawn, the mission’s organisers said two Israeli “warships” had approached fast and encircled two of the flotilla’s boats.

All navigation and communication devices went down, in what one organiser on board described as a “cyber attack”.

A video posted on the flotilla’s Instagram page showed the silhouette of what appeared to be a military vessel with a gun turret near the civilian boats.

Last week the flotilla was attacked by drones, which dropped stun grenades and itching powder on the vessels, causing damage but no injuries. Israel did not comment on that attack, but has said it would use any means to prevent the boats from reaching Gaza, arguing that its naval blockade is legal as it battles Hamas militants in the coastal enclave.

They are not seeking to help, they are seeking an incident

Italy and Greece on Wednesdayyesterday jointly called on Israel not to hurt the activists on board and called on the flotilla to hand over its aid to the Catholic Church for indirect delivery to Gaza – a plea the flotilla has previously rejected.

Israeli officials have repeatedly denounced the mission as a stunt.

“This systematic refusal [to hand over the aid] demonstrates that the objective is not humanitarian, but provocative. They are not seeking to help, they are seeking an incident,” Jonathan Peled, the Israeli ambassador to Italy, said in a post on X.

At a press conference held by organisers yesterday, Francesca Albanese, the top UN expert on Palestinian rights, said any interception of the flotilla “would be yet another violation of international law, the law of the sea” since Israel had no legal jurisdiction on waters off Gaza.

Israel has imposed a naval blockade on Gaza since Hamas took control of the coastal enclave in 2007 and there have been several previous attempts by activists to deliver aid by sea.

In 2010, nine activists were killed after Israeli soldiers boarded a flotilla of six ships manned by 700 pro-Palestinian activists from 50 countries.