Tunisian authorities on Tuesday rejected claims by an international aid flotilla that one of its vessels was struck by a drone while delivering humanitarian supplies to Gaza, saying there was ‘‘no basis in truth’’ to the reports as they investigated a fire aboard the ship.

The Global Sumud Flotilla, a coalition of dozens of boats from 44 countries carrying food, water and medical supplies, said overnight that a drone had struck one of its main vessels, which sails under the Portuguese flag. The group posted surveillance footage showing a flash of light landing on the vessel and a subsequent blaze on deck, and said no one aboard was injured.

The Tunisian Interior Ministry issued a statement saying reports of a drone strike at Sidi Bou Said port "have no basis in truth" and that authorities were investigating the cause of a fire that broke out on the deck. Tunisian officials did not identify a likely source for the blaze in their statement.

At a press conference in Tunis, members of the flotilla denounced what they called an act of intimidation and said the mission to deliver aid to Gaza would continue. Portuguese activist Miguel Duarte, who said he was aboard the vessel, told reporters he saw a drone hovering a few meters above the deck before an explosion and a rapid flare-up of flames. "The drone stood a few seconds on top of a bunch of life jackets and then dropped a bomb," he said, adding that crew used fire extinguishers to put out the blaze and that all aboard were safe.

The flotilla movement, which includes participants from 44 countries and prominent activists, aims to challenge Israel's naval blockade of the Gaza Strip and deliver humanitarian supplies to civilians. Swedish climate activist Greta Thunberg is among those listed as associated with the effort.

The blockade has been in place since Hamas took control of Gaza in 2007 and has continued through Israel's wartime operations following Hamas's Oct. 2023 attack on Israel. Israel says the blockade is intended to prevent weapons smuggling to the territory; organizers of aid missions argue that civilians in Gaza face severe shortages of essential goods and medical supplies.

Video posted by the group and circulated on social media shows a bright flash and a short-lived fire on a vessel's deck; the footage has not been independently verified. The flotilla said the strike damaged the main deck and below-deck storage but did not cause injuries.

Tunisian authorities said they were examining the footage and evidence from the scene. International reactions to the incident were limited on Tuesday as governments awaited further information from Tunisian investigators and from the flotilla organizers.

A Reuters statement accompanying early reports noted the Tunisian ministry's denial and the flotilla's claims. The flotilla held the press conference in the Tunisian capital on Tuesday, where participants waved Palestinian flags and called for continued efforts to deliver aid to Gaza.

Reporting from multiple outlets contributed to this article.