Organisers of a Gaza-bound flotilla say one of their main ships was hit by a drone — a claim authorities have rejected.
The vessel, known as the Family Boat, is part of the Global Sumud Flotilla (GSF). The international initiative seeks to deliver humanitarian aid to war-torn Gaza via civilian boats supported by delegations from 44 countries.
The alleged attack on the boat — carrying the GSF's steering committee, which includes climate activist Greta Thunberg, as well as two Australians — occurred while it was anchored about 80 kilometres from the port of Sidi Bou Said in Tunisia.
"The Global Sumud Flotilla (GSF) confirms that one of the main boats ... was struck by what is suspected to be a drone," the organisers said on social media.

The GSF said the attack occurred while the vessel was anchored about 80km from the port of Sidi Bou Said in Tunisia. Source: AAP / EPA / Mohamed Messara
They shared security camera footage from the boat in which a humming sound can be heard, before a flash of light illuminates the frame.
Another video shared on the GSF's social media pages shows crew members looking up and jumping back before a flash of light and sound of an explosion is heard.
But Tunisian authorities have disputed the allegation and say the explosion originated inside the boat.
"According to preliminary findings, a fire broke out in the life jackets on board," Tunisian national guard spokesman Houcem Eddine Jebabli told Agence France-Presse.
He said the investigation was ongoing, but "no drones" had been detected.
Reports of a drone are "completely unfounded", the national guard said in a statement on its official Facebook page, suggesting that the fire may have been caused by a cigarette.
Saif Abukeshek, a spokesperson for the GSF, blamed Israel for the attack.
"There is no other authority that would do such an attack, such a crime, except the Israeli authorities," he said in a video posted on the GSF's Instagram page.
SBS News has contacted the Israel Defense Forces for comment.
The boat was carrying Australians Dr Bianca Webb-Pullman and Yusuf Omar. A statement from the families of Australians involved in the flotilla said: "While not physically injured, the traumatisation of a drone attack causing fire on a boat at sea is both serious, and illegal"
Australia's Department of Foreign Affairs (DFAT) said it was "aware of an alleged drone attack" on the vessel.
"We stand ready to offer consular assistance, to any Australian citizen, should it be requested," a DFAT spokesperson said in a statement.
After the alleged strike, dozens of people gathered outside the Sidi Bou Said port, where the flotilla's boats were located at the time of the incident, waving Palestinian flags and chanting "Free Palestine", a Reuters witness said.
Israel has imposed a naval blockade on the coastal enclave since Hamas took control of Gaza in 2007, saying it aims to stop weapons from reaching the militant group.

Pro-Palestinian supporters in Tunisia gathered to protest the alleged attack. Source: AAP / EPA / Mohamed Messara
Israel's subsequent military assault against Hamas has killed over 64,000 Palestinians, Gaza's health ministry said, while a global hunger monitor said part of the enclave is suffering from famine.
Israel sealed off Gaza by land in early March, letting in no supplies for three months and sparking the widespread shortage of food. It has accused Hamas of stealing aid for its own fighters or to sell to finance its operations, an accusation Hamas denies.
In June, Israeli naval forces boarded and seized a British-flagged yacht carrying Thunberg, among others. Israel dismissed the aid ship as a propaganda stunt in support of Hamas.
And in July, another boat carrying 21 activists, including two Australians — Tan Safi and Robert Martin — was intercepted by Israeli forces. They were detained and deported.
— With additional reporting by the Agence France-Presse and Reuters news agencies.