An Italian peace activist was murdered in Gaza as a result of a feud between Hamas and another militant group, the ultra-radical Salafi.

The body of Vittorio Arrigoni, 36, who was previously kidnapped and held for ransom by armed assailants, was found by Hamas police officials in an apartment in the Gaza Strip.

The kidnappers had released a video of Arrigoni on YouTube in which they demanded the release of a number of Salafi militants who had been arrested by Hamas security forces in Gaza. They said they would kill the hostage by 5 pm (local time) Friday of their demands were not met.

They specifically demanded the release of their leader, Sheikh Abu Walid al-Maqdasi, who was arrested by Hamas police last month.

However, the Hamas interior ministry said the Italian man was murdered quickly after he was abducted midday on Thursday.

Hamas spokesman Ehab al-Ghussein said he was killed in an awful way and that the kidnappers has likely planned to murder him from the beginning.

Hamas denounced the murder as a crime that does not reflect the values, morals, religion and customs of the people of Gaza.

A Gaza-based correspondent for Al Jazeera said: Hamas has rounded up a lot of Salafi members since this news came out to try and get more information but at this stage they have told us that there has only been one confirmed arrest. Hamas is very keen to say that the security situation in Gaza is solid. It's been really pushing home the message that Hamas is in control and that Gaza is safe.”

The Italian foreign ministry in Rime condemned what it described as a barbaric murder and a vile and irrational gesture of violence on the part of extremists indifferent to the value of a human life.

According to reports, Arrigoni worked with a pro-Palestinian group called the International Solidarity Movement (ISM).

The Al Jazeera reporter said: The little that we do know about why [Arrigoni] was kidnapped in Gaza has come from YouTube video that those responsible posted online. In that video they said they would not release him until all of Salafi prisoners who are currently in jail in Gaza, are freed. They also called for release of one of the main Salafi leaders. They said they would not free him until those people were freed from jail. That seems to be the motive behind the case.

However, according to Al Jazeera there is some confusion over who the kidnappers really are.

We don't know which group was behind it. At this stage the main Salafi groups are denying any responsibility. So the situation is quite confusing as who is exactly behind it, the correspondent said.

Salafists, which advocates an austere form of Sunni Islam based on practices of earliest Muslims, believe Hamas is too moderate.

Arrigoni was the first foreigner to be abducted in the Gaza Strip since Alan Johnston, the BBC journalist who was held for 114 days by a group calling itself named the Army of Islam. He was released in 2007.