Palestinian factions have condemned the murder of Italian peace activist Vittorio Arrigoni found dead in Gaza early Friday morning.

Salafist extremists in Gaza were suspected of kidnapping Arrigoni, an activist for the International Solidarity Movement, last seen alive in a video posted online Thursday.

In the video, the kidnappers threatened to kill Arrigoni unless Hamas released Salafist prisoners by Friday evening. Before the deadline passed, however, Hamas said his body was found hanged in a home northwest of Gaza City.

The government in Gaza said the "heinous crime" did not reflect Palestinians' values, religion, customs or traditions. In a statement, the government said it would bring the perpetrators to justice.

The government extended its condolences to Arrigoni's family and urged all Palestinians in Gaza to attend his funeral procession as a message that Palestinians rejected the murder of the peace activist who was known to all residents as a supporter of the Palestinian cause.

Hamas denounced the activist's murder, which it said was carried out by a "mentally deviated and outlawed group."

Hamas spokesman Fawzi Barhoum said the killing was "a disgraceful act." He praised Arrigoni's role and the work of all peace activists "in conveying the suffering and concerns of all Palestinians, in particular those in Gaza."

Barhoum added: "We extend our condolences to Vittori’s family and people."

The spokesman said the group responsible for the killing aimed to undermine the stability of the besieged coastal enclave, to defame the reputation of Palestinians and to isolate Gaza from international solidarity.

Fatah said the murder was a terrorist crime and an act of betrayal that only served Palestinians' enemies.

The killing went against Palestinians' reputation as a civilized people who worked hard to gain freedom and build a democratic, enlightened society, Fatah spokesman Ahmad Assaf said.

"This kind of crime is alien to the Palestinians," he said, adding that respect for human dignity was at the core of Palestinian people's moral values.

Islamic Jihad also denounced the "grotesque crime." The movement said the perpetrators served the Israeli occupation which was inciting against the solidarity movement with the Palestinian cause.

The party called on the Gaza government and its security forces to harshly punish Arrigoni's killers.

The Palestinian People's Party said Arrigoni's murder was "a moral and national crime," and called for the perpetrators to be severely punished.

"Vittori left his family and homeland behind to live with the Palestinians despite attacks and siege to convey the suffering of the Palestinians to the whole world in his writing," PPP said in a statement.

The Popular Resistance Committees condemned the murder as "a cowardly act."

Secretary General of the Palestinian National Initiative Mustafa Barghouthi expressed his deep sorrow at the "shocking criminal act" which he said only served the interests of the enemies of the Palestinian people.

Barghouthi offered his condolences and sympathy to Arrigoni's family, adding that the murder was "totally incompatible with Palestinian and human values."

Meanwhile, a Salafi group in Gaza At-Tawheed wa Al-Jihad denied involvement in Arrigoni's abduction and murder in a statement but said the killing was "a natural outcome of the policy of the government carried out against the Salafi."