JERUSALEM, Apr 15, 2011 (AFP) - The pro-Palestinian International Solidarity Movement said on Friday it was distraught at news that an Italian member had been found murdered in the Gaza Strip.

Vittorio Arrigoni was found dead early on Friday morning, after a Salafist group posted a video of him online and threatened to kill him unless an unspecified number of their members were released by Gaza rulers Hamas.

Huwaida Arraf, a co-founder of the International Solidarity Movement (ISM), told AFP she was shocked and horrified by news of Arrigoni's murder.

"I was in complete shock, not for a minute, I can't even tell you I thought even one percent that they would hurt him, that they would end up killing him," she said. "I spent the night crying."

"Just thinking of the video of the last moments of life, in Gaza which he loved so much, that those were his last moments, was just really hard to swallow."

The video posted on YouTube showed a bruised and bloodied Arrigoni, his eyes apparently covered with black duct tape and his hands bound behind his back.

His kidnappers identified themselves as belonging to a previously unknown group called The Brigade of the Gallant Companion of the Prophet Mohammed bin Muslima.

They demanded the release of "all our prisoners," naming in particular an imprisoned jihadi leader called Sheikh Hisham al-Suedani and threatened to kill Arrigoni in 30 hours from 11:00 am (0800 GMT) on April 14.

Arraf said Arrigoni had been living on-and-off in the Gaza Strip since 2008, when he first arrived in the Palestinian territory on a boat chartered by the ISM.

In late 2008, he was arrested by Israeli troops while accompanying Palestinian fishermen off Gaza's coast, and was deported. He later returned and had been living in Gaza City.

Arraf said Arrigoni, 36, was the last person she could imagine being targeted in Gaza.

"He's been there since 2008. He's very well-known, he lives among the people. He's just got this dynamic, humanitarian personality," she said.

"I even thought that whoever has him is going to see his humanity and just let him go so when I heard what happened to him I was totally shocked."

Arrigoni, who had been a member of ISM since at least 2004, was in Gaza during Israel's devastating December 2008-January 2009 Operation Cast Lead and wrote a book about his time there, she said.

Arraf said ISM had never received threats from Palestinians, though two members of the organisation were killed a few weeks apart in 2003 by Israeli troops in the Gaza Strip.

"There'd really never been any threats against ISMers in Gaza, especially not against him. The people in Gaza have really warmly welcomed ISM because we stand in solidarity with them."

Arraf said no decision had been made as to whether ISM activists in Gaza would leave, but that it would be up to volunteers on the ground.

"I personally don't think it's necessary that they leave, because this is such a random act, crazy people are acting against the will of the people."

sah/bpz

Copyright AFP 2011.