"Interfering with our passage is unlawful and any attack or interception constitutes a war crime."

The group issued a statement, saying the captain of one of the vessels was forced to make a sharp manoeuvre in order to avoid a collision.

The warship came "dangerously close" to the vessel for several minutes, and onboard communications were disabled remotely.

The Israeli ship then proceeded to harass another vessel with similar manoeuvres.

"These reckless and intimidatory manoeuvres placed participants at serious risk," the GSF says.

"Interfering with our passage is unlawful and any attack or interception constitutes a war crime."

The GSF aims to break Israel’s naval blockade on the Gaza Strip, and deliver humanitarian supplies.

They they are entering a "high-risk zone" as they are now within 150 nautical miles from Gaza.

Italy, whose boats are escorting the flotilla, have issued a final warning for the group to turn back.

It comes after the flotilla was struck by drones.

The Global Sumud Flotilla said in a statement: “Multiple drones, unidentified objects dropped, communications jammed and explosions heard from several boats.”

“We are witnessing these psychological operations firsthand, right now, but we will not be intimidated.”