Palestinian civilians joined members of the Hamas police and security forces on Monday for a funeral to mourn the death of an Italian activist killed by a Salafist group last week.

Hundreds of people gathered in Gaza City and at the Rafah border crossing to pay to their respects to Vittorio Arrigoni, 36, who was found hanged in an empty house in northern Gaza on Friday, hours after he was kidnapped.

His body was carried from Gaza City's Shifa Hospital in a wooden coffin draped in a Palestinian flag and strewn with rose petals.

Mourners carrying signs bearing his motto: "Stay human" surrounded the coffin, as Hamas police and security officials saluted during the state funeral ceremony given in his honour.

A procession of mourners in cars, waving Palestinian flags from their vehicles, accompanied Arrigoni's body from the hospital, south along Gaza's main road to Rafah.

Others lined the route, holding pictures of Arrigoni, who was a member of the pro-Palestinian International Solidarity Movement and a well-known figure in Gaza City.

At Rafah, pallbearers carrying the coffin wept as Palestinians waved banners reading "No, no to militancy and terrorism, yes, yes to freedom".

Hassan Al Saifi, a representative of Gaza's Hamas government, addressed the mourners, pledging that the group would bring Arrigoni's killers to justice.

Hamas security forces have so far arrested four people in connection with the murder, but have said at least three suspects remain at large: Bilal Al Omari, Abdul-Rahman Al Breizat, a Jordanian, and Mohammed Al Salfiti, a Hamas policeman.

A previously unknown Salafist group claimed responsibility for Arrigoni's kidnap, issuing a video on Thursday night showing the Italian bruised and bloodied, and demanding the release of a local Salafist leader held by Hamas.

Hamas security forces found Arrigoni's body shortly afterwards.

Saifi praised the Italian activist as a "symbol of humanity", saying "generations of Palestinians will keep alive the memory of this pure man".

Friends of Arrigoni, who had lived in Gaza for much of the past three years, said his passion for the Palestinian cause would live on.

"The idea that Vittorio died for will not die, and it will remain until the end of the occupation," said Osama Qashwan, a Palestinian-British activist.

Inge Neefs, a Belgian member of the International Solidarity Movement, agreed.

"His idea of the humanitarian defence of the Palestinian people is a humanitarian idea that will not die," she told AFP.

Wissam Abu Warda, a Palestinian friend of Arrigoni's, described the Italian as "the symbol of freedom, who gave our youth the power to continue our fight for freedom".

Arrigoni's body was transferred across the Rafah crossing into Egypt after the funeral ceremony, and is scheduled to travel onwards to Cairo from there, in accordance with his family's wishes, Hamas officials said.