Its organizers said a ship carrying humanitarian aid and militants to Gaza was blown up by drones and disabled people sailed toward Palestinian territory in international waters near Malta.
"At 00:23 Malta, conscience, a Free Fleet Alliance ship was directly attacked in international waters," the group said in a statement.
"Armed drones attacked the front of an unarmed civilian ship, causing two major fires and serious violations of the hull," it said.
The strike appears to be targeting the generators of the ship earlier on Friday, leaving the ship powerless and at risk of sinking, activists said. Images posted to social media by the Freedom Flotilla Alliance showed fierce fires and two explosions on board.
There is no confirmation or further evidence that the drone caused the explosion, but images of conscience provided by Cypriot authorities showed serious damage.
The Malta government said in a statement on Friday that twelve crew members and four civilians were "confirmed for safety." "There were 12 crew members and four civilian passengers on board; no casualties," the statement said, adding that nearby tugs had been directed to help the ship.
The group said militants from 21 countries are joining a "mission to challenge Israel's illegal and deadly siege of Gaza and to provide a desperate need for life-saving assistance."
"The Israeli ambassador must be called and answered violations of international law, including ongoing blockades and bombing of our civilian ships in international waters," the statement said.
Israel has not commented on the allegation.
Conscience left the Tunisian port on Tuesday and arrived in the area, which was reportedly attacked on Thursday morning, according to monitoring website Marinetraffic. The ship is heading to a point near Malta to take over activists from a smaller vessel, including climate change activist Greta Thunberg.
Dunberg confirmed to Reuters that she was in Malta and should have boarded the ship.
"I am part of the team that should board the ship today and continue the voyage to Gaza, one of many attempts to open the humanitarian corridor and do our best to continue our efforts to break the Israeli illegal attack on Gaza," she said. "This attack caused explosions and major damage to the ships, which made it impossible to continue the mission."
The group said it has been organizing nonviolent actions amid media outages to avoid any potential damage.
A previous voyage from the Southern Union of Turkey ended in a bloody incident as Israeli troops stormed into Mavi Marmara ships, killing 10 people and injuring 28 people.
The Turkish Foreign Ministry said that when the incident occurred, the Turkish nationals were in a state of conscience.
"We condemn the attack on a civilian ship with the strongest stern condemnation," it said, noting that "there are allegations that Israeli drones target the ship."
"Everything necessary will be done to reveal the details of the attack as soon as possible and bring the perpetrators to justice," it said.
Israel imposed a tight blockade on Gaza two months ago, not allowing food, fuel, medicine or other items to enter the territory, and resumed strong military operations in Gaza in mid-March after a fragile ceasefire collapse.
Humanitarian groups in Gaza have distributed its last stock of flour and other foods. Officials in the destructive Palestinian territory said Friday that kitchens that provide basic meals for those without other options will be closed within a week to 10 days.
On Friday, the ICRC said it would not have access to the food, medical and lifesaving supplies needed for many Gaza programs unless aid is restored immediately.
"Aid must be allowed to enter Gaza. Hostages must be released. Civilians must be protected." "Without immediate action, Gaza will further fall into chaos that humanitarian efforts will not be alleviated."
Medical staff at the remaining medical facilities in Gaza said they are now prioritizing cases to ensure available medical stocks are retained for the worst stocks. Drugs for chronic diseases such as cancer, diabetes and hypertension are actually unavailable, officials said.
"I don't know how people manage it. They lose everything. Displacement continues every day, and more and more people are looking for shelter and everything they need to survive."
A UN team has been sent to the destructive Palestinian territory to assess the levels of malnutrition and the risk of famine.
Israeli officials believe Hamas usually steals aid, distributing it to fighter planes or selling it is reasonable. Aid officials in Gaza have denied any widespread theft in recent months.
Israeli media reported on a plan that used private contractors to distribute food from a centralized hub protected by the Israeli military to censored Palestinians. Humanitarian officials in Gaza said the plan was not feasible and could be illegal.
The war in Gaza was triggered by Hamas's attack on southern Israel in October 2023, killing about 1,200 people, mostly civilians. Hamas - The Ministry of Health, which operates Gaza, said Thursday that at least 2,326 people have been killed since Israel resumed strikes, causing an overall death toll since the war broke out, which is 52,418, mainly civilians.