The Global Sumud Flotilla, carrying food and medicines for besieged Palestinians in Gaza has been intercepted by the Israeli navy around 70 nautical miles from the enclave’s shores, with organisers alleging cyber-attacks, drone strikes and threats of boat seizures.

The flotilla, comprising over 40 civilian boats and nearly 500 passengers, includes UN representatives, parliamentarians, human rights activists, lawyers, and environmental campaigner Greta Thunberg.

Pakistani former senator Mushtaq Ahmed Khan is also among the participants.

According to aid workers onboard, communication with flotilla members has been cut off, and there are unconfirmed reports of detentions and possible boat seizures.

Organisers said they had vowed not to return “until Palestine is free” and insisted they would continue their mission despite all risks.

Earlier, Reuters reported that two Israeli warships dangerously surrounded the vessels Alma and Sirius as the flotilla approached Gaza’s maritime zone.

Brazilian activist Thiago Ávila, one of the organisers, said all navigation and communications systems suddenly shut down in what he described as a “cyber-attack.”

Israel’s Foreign Ministry said the flotilla had been warned to change course, claiming it was entering “an active war zone” and violating a “lawful naval blockade.”

Officials added that Israel had previously offered “safe and peaceful routes” for aid delivery, including through third parties, but flotilla organisers rejected this.

Israeli forces reportedly threatened to seize the boats if they did not stop. In response, organisers said: “If you block us, you will commit an international crime.”

Earlier, Reuters reported that the flotilla organisers said Israeli vessels approached some of its boats and engaged in “dangerous and intimidatory manoeuvres” on Wednesday as it neared the war-stricken strip.

The mission’s organisers said two Israeli “warships” had approached fast and encircled two of the flotilla’s boats, Alma and Sirius.

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

The flotilla appeared to have recovered some communications. Israeli officials did not immediately respond to a request for comment.

‘Dangerous manoeuvres’, drone attack

The mission is the latest sea-borne attempt to break Israel’s blockade of the Palestinian enclave to deliver food and medicine. It is currently within 120 nautical miles of Gaza’s coast, inside an area that Israel is policing to stop any boats approaching.

It is expected to arrive on Thursday morning if not intercepted.

“These hostile actions placed unarmed civilians from over 40 countries in grave danger,” the flotilla said in a statement, adding that it will continue its course towards Gaza.

It was not clear who operated the vessels that approached the flotilla. A video post on the flotilla’s Instagram page showed the silhouetted outline of what appeared to be a military vessel with a gun turret near the civilian boats.

Reuters confirmed that the video was filmed from the vessel Sirius because its rigging and lines matched file imagery of the boat.

Reuters could not confirm the identity of the other vessel in the video or when the video was taken.

The flotilla has raised tensions in recent days since it 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 will 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.

Italy and Spain deployed naval ships to help with any rescue or humanitarian needs, but have said they will not engage militarily. Turkish drones have also followed the boats.

However, Italy and Spain said they would stop following the flotilla once it got within 150 nautical miles (278 km) of Gaza for safety reasons.

Past attempts to deliver aid

At the press conference held by organisers on Wednesday, 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 to Gaza by sea, both during the latest conflict and others.

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

In June this year, Israeli naval forces detained Thunberg and 11 crew members on a small ship organised by a pro-Palestinian group called the Freedom Flotilla Coalition as they approached Gaza.

Italy and Greece, on Wednesday, jointly called on Israel not to hurt the activists aboard and called on the flotilla to hand over the aid to the Catholic Church for indirect delivery to Gaza - a plea the flotilla has previously rejected.