Greta Thunberg’s flotilla carrying humanitarian aid toward Gaza was struck by a drone in Tunisian waters, its organizers said late Monday.

Crew members said the drone hit Global Sumud Flotilla’s (GSF) main vessel when its was anchored outside the port of Sidi Bou Said in Tunisia. The boat sustained damaged to its main deck and below-deck storage, according to footage published on X by the GSF.

“The family boat has been officially attacked. The drone came right above it, released the bomb, and it exploded and the boat was on fire. Everyone on that boat is okay … they have bombed a boat, once again, with civilians on it. In Tunisian territory,” said Yasemin Acar, one of the six activists who was on board.

“The main flotilla boat, Family, has been attacked. By a drone. Of course, it will have to be verified … if it’s confirmed that there has been an attack on this flotilla, there has been an attack on Tunisia,” Francesca Albanese, United Nations special rapporteur on the occupied Palestinian territories and a prominent critic of Israel, said in a video.

Tunisian authorities, however, denied the reports of a drone attack.

Houcem Eddine Jebabli, a spokesperson for Tunisia’s national guard, said an investigation was “ongoing” but “no drones have been detected,” calling the reports “completely unfounded.”

“According to preliminary findings, a fire broke out in the life jackets on board a ship anchored 50 miles from the port of Sidi Bou Said,” he added, suggesting that fire might have been caused by a cigarette.

The GSF flotilla set sail from Barcelona last week and arrived in Tunisia over the weekend. It comprises about 20 vessels carrying pro-Palestinian activists from 44 nations heading toward Gaza to deliver humanitarian aid amid Israel’s ongoing war on Hamas.

Israeli authorities have dismissed attempts to ferry aid to Gaza as publicity stunts. In June, the country’s forces intercepted another aid ship that Thunberg was on.

According to the Integrated Food Security Phase Classification (IPC) report published in late August, famine conditions in Gaza are “entirely man-made” but could be “halted and reversed” if immediate action is taken.