Australian photographer Kate Geraghty was electroshocked on the arm by Israeli soldiers who stormed a flotilla of boats heading to Gaza, a fellow passenger said on Wednesday.

One of the first to be released from detention center on Wednesday (AEST) was organizer with the Free Gaza Flotilla, Huwaida Arraf, a dual U.S./Israeli citizen who claimed she was aboard the U.S.-flagged vessel Challenger 1 along with Australian Fairfax journalist Paul McGeough and Geraghty.

"They were on the Challenger 1 with me and I know that Kate was tasered and was not feeling well," Arraf told ABC Radio 702, adding that Taser is an electroshock weapon that uses electrical current to disrupt voluntary control of muscles.

"She was trying to send out some pictures before our boat was taken over but all of our satellite capabilities were jammed and she was not able to do that," Arraf said.

Once the commandos boarded the vessel, one of their first acts was to seize all communication equipment, cameras and memory cards, Arraf added.

"I did not see her being tasered but when we were all gathered into a room when they had subdued all of us and taken over the boat, she did show us her wound on her arm and she said that she wasn't feeling well and that she was hurt, but I didn't see the actual tasering and how she reacted to it," Arraf said.

The Fairfax photographer along with senior Fairfax journalist Paul McGeough have been detained by Israeli authorities since Monday afternoon (AEST) when the naval commandos boarded the ships and took control.

At least nine people were killed during the takeover, with others injured and more than 100 detained.