Israeli forces reportedly fired at some of the vessels using rubber bullets.

A total of 48 boats were intercepted in the Mediterranean, with approximately 400 people detained.

Allegations of mistreatment

Mr Deasy told RTÉ that activists were stripped and held in what detainees referred to as a “torture chamber”, where “pretty much everyone” on the ship was beaten.

He said hearing more than 170 people — many of them close friends — allegedly being beaten was “probably the worst” part of the detention.

Mr Deasy described the treatment by Israeli authorities as “sheer brutality”.

"I got a rifle bashed into my back and that was the first realization of just how brutal these were.

"But it only escalated from that point on. The sheer violence and aggression used on people for no reason was just indescribable."

He alleged that activists were stripped of their clothing, leaving only an underlayer “to expose them to the cold as much as possible”.

"They would take us into the container [on the ship they were detained on]. That became known as torture chamber. It was where the beatings would happen. And that is where pretty much everyone on the ship got beaten.

"And then you would be thrown through the door into the air to your comrades. But that was probably the hardest part of it, listening to all the beatings. As we were the first boat intercepted, we listened to over 170 people getting beaten, and it echoed throughout the yard we were being kept in."

Legal action planned

Mr Deasy said activists underwent medical examinations and gave statements on Thursday night.

He said they are preparing legal cases against Israel over their treatment.

The activists have since been able to contact family members and have booked flights to return to Ireland on Saturday.

"The sense of tickets being organised for us to fly home and being in contact with our family at home is a very reassuring thing for us. Our situation is coming to an end after what we've been through," Mr Deasy said.

"But the fact that we came here in solidarity with the Palestinian people, and 9,500 Palestinians are held in captivity and go through that every single day just for being Palestinian, and the fact that we knew there probably will be a hope that we will get out and released after a while, but they have no hope.

“People have to be held accountable. We were badly treated ....but this has been going on for decades.”

The activists were deported to Turkey and are awaiting flights back to Ireland on Saturday.

Fourteen Irish citizens, including Margaret Connolly, sister of President Catherine Connolly, were among those deported from Israel on Thursday.