Activists on a Gaza aid flotilla that alleged it was targeted by a "drone attack" off Tunisia overnight said Tuesday they remained "determined" to reach the war-ravaged Palestinian territory.

The flotilla organisers had said late Monday that one of their boats was hit by a suspected UAV off the coast of Tunisia, but authorities there said "no drones" had been detected.

"Our will is stronger and we are more determined (than ever) to break the blockade against Gaza," Tunisian organiser Ghassen Henchiri told a crowd in Tunis.

Nadir al-Nuri, a member of the steering committee, told AFP that the flotilla was set to depart the Tunisian capital on Wednesday as scheduled.

The flotilla, which aims to break Israel's blockade of Gaza, arrived in Tunisia at the weekend and was anchored off the coast of Sidi Bou Said, north of Tunis, when it reported the incident.

Some members of the flotilla said they saw the drone, adding that the boat's bow caught fire immediately after.

Authorities dismissed reports of a drone strike as "completely unfounded", suggesting the fire may have been caused by a cigarette butt.

Tunisian national guard spokesman Houcem Eddine Jebabli told AFP overnight "no drones have been detected".

But security footage posted by the flotilla organisers later showed a burning mass falling from a distance onto the ship.

- 'Drone above my head' -

Asked by AFP about the reported attack, Palestinian activist Saif Abukeshk implicitly blamed Israel.

"No party has an interest in preventing the flotilla from setting sail except the occupying state," he said.

The Israeli military did not immediately respond to AFP's request for comment.

The vessel was in Tunisian waters when a fire broke out and was quickly extinguished, according to an AFP journalist who arrived shortly after the flames had been doused.

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Tunisian protesters shout anti-Israeli slogans and wave Palestinian flags at the Port of Sidi Bou Said near Tunis on September 9, 2025 / © AFP

The flotilla organisers said that the boat suffered no substantial damage and that none of the six people on board at the time was hurt.

Among them was Portuguese activist Miguel Duarte, who told reporters in downtown Tunis on Tuesday that he saw a drone drop an explosive device.

"I was on the deck on the back part of the ship, and I heard a drone," he said. "I came out of the cover of the deck to see a drone hovering about three or four metres above my head."

"I called my fellow crew members," Duarte added. "Then we saw the drone move to the (front) part of the deck. It stood for a few seconds on top of a bunch of life jackets and then dropped a bomb... there was a big flame."

The flotilla organisers denounced the incident as "acts of aggression aiming to derail (its) mission".

"We remain united and determined to leave tomorrow," said Franco-Palestinian European Parliament member Rima Hassan in Tunis.

- 'State security' -

Organisers declined to react to the authorities' account of the incident, with Henchiri saying it concerned "state security".

Francesca Albanese, the United Nations special rapporteur for the Palestinian territories who lives in Tunis, told reporters at the port overnight that if the a drone strike is confirmed, it would amount to an "aggression against Tunisia".

The Sidi Bou Said port lies about two kilometres (1.2 miles) away from the Tunisian presidential palace in Carthage, which can be seen from its harbour.

The incident comes as Gaza endures a war sparked by the Hamas attack on Israel in October 2023.

The United Nations declared famine last month in parts of Gaza, warning that 500,000 people face "catastrophic" conditions.

The Global Sumud Flotilla -- "sumud" meaning steadfastness in Arabic -- describes itself as an independent group not linked to any government or political party.

Among its high-profile participants is Greta Thunberg, who addressed pro-Palestinian campaigners in Tunisia on Sunday.

The flotilla is due to resume its voyage for the Gaza Strip on Wednesday, after being delayed multiple times by weather conditions and other issues.