The body of an Italian activist who was kidnapped hours earlier by Muslim extremists was found in a house in Gaza City early Friday morning, Hamas security officials said.

A file photo taken on June 3, 2010 shows Italian peace activist Vittorio Utmpio Arrigoni waving a Palestinian flag aboard a ship during an activity calling for lifting the Israeli siege on Gaza, at Gaza seaport. An unknown radical Muslim group on Thursday said it kidnapped Arrigoni, 36, in the Gaza Strip and demanded Hamas authorities to free members of the Salafi group. [Ashraf Mohammed/Xinhua]

The security officials said the Italian activist was very likely strangled as there were no gunshot wounds found in his body. Two suspected kidnappers were arrested in the raid.

The pro-Palestinian International Solidarity Movement had identified the kidnapped activist as Vittorio Arrigoni, 36, a member from Italy. He came to Gaza on the first ships that challenged an Israeli blockade on Gaza in 2008.

An unknown Muslim group said Thursday it kidnapped an European activist in the Gaza Strip and demanded Hamas authorities free members of the Salafi group.

The abductors released a video showing the hostage blindfolded and called on Hamas to release the leader of Al-Tawheed and Al-Jihad group within 30 hours starting from 0900 GMT Thursday.

It threatened to execute the hostage if Hamas did not release the prisoners.

The video said the hostage was Italian, and identified his first name as "Victor."

Hamas, which has controlled Gaza since 2007, launched several crackdowns on supporters and members of Salafi groups, which follow more hardliner conception of Islam than Hamas.