An Israeli naval vessel rammed a Gaza-bound humanitarian aid boat in international waters, organizers of the Global Sumud Flotilla said Tuesday, adding that communication with activists aboard the Sirius vessel was lost after the collision.

The flotilla's crisis committee said the Israeli ship deliberately struck the rear section of the civilian aid boat while attempting to stop it from sailing toward Gaza to break Israel's blockade and deliver humanitarian assistance.

According to the statement, Israeli forces carried out "military maneuvers" around the vessel, creating artificial waves and spraying high-pressure water before the collision occurred.

Organizers described the incident as a "lawless and barbaric attack" that directly endangered the lives of activists and crew members aboard the unarmed vessel.

"The Israeli intervention constitutes a clear act of piracy," the committee said, adding that satellite communication with the Sirius was severed immediately after the impact and the fate of those on board remains unknown.