Organisers of a Gaza-bound flotilla carrying aid and pro-Palestinian activists have said they heard explosions and saw multiple drones that targeted some of their boats, currently situated off Greece, AFP reports.

“Multiple drones, unidentified objects dropped, communications jammed and explosions heard from a number of boats,” the Global Sumud Flotilla said in a statement, without adding whether there were any casualties.

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

German human rights activist and flotilla member Yasemin Acar said in a video she posted on Instagram that five vessels had been attacked.

“We are carrying only humanitarian aid,” she said. “We have no weapons. We pose no threat to anyone. It is Israel who is killing thousands of people (and) starving a whole population.”