Global Sumud Flotilla says a fire was started but Tunisian authorities deny that a drone was involved.

Tunisia’s National Guard spokesman told Mosaique FM radio that reports of a drone attack on the flotilla “have no basis in truth”, Reuters reported.

He added that an initial inspection indicated the explosion originated inside the vessel.

In a series of videos published to their Instagram, spokespeople for the flotilla said an “incendiary device” caused a fire onboard the vessel, which the crew was able to extinguish.