Kidnappers apparently behind the heinous murder of an Italian activist in Gaza belong to the Salafist movement whose extremism is more hardline than that of Hamas.
The Brigade of the Gallant Companion of the Prophet Mohammed bin Muslima posted a video online Thursday showing the activist Vittorio Arrigoni blindfolded, bloodied and bruised, before they reportedly hanged him.
Previously unheard-of, they indicated in the video they belong to the Salafist movement that accuses Hamas, the Islamist group that rules the Gaza Strip, of being too weak with Israel and of failing to uphold Islamic law in the Palestinian enclave.
|One of the Gaza Salafist groups: - Jund Ansar Allah, or the Soldiers of the Companions of God ~ leader killed in Rafah shootout in 2009 shortly after this picture was taken.|
The radical movement derives its name from the Arabic word "salafi" meaning forebears, and espouses an austere form of Sunni Islam that seeks a return to practices that were common in the early days of the faith.
There are five major Salafist groups in Gaza - Jaish al-Islam, Jund Ansar Allah, Tawhid wa Jihad, Jaish al-Umma and Ansar al-Sunnah - which are said to have hundreds of members.
|More from mosque scene above.|
Their religious observances and refusal to abide by various ceasefires have set them on a path of confrontation with Hamas.
And though small in numbers, the groups have had a disproportionate impact.
By launching hundreds of crude rockets from the coastal enclave into the Jewish state, they have attracted the wrath of both Israel and Hamas.
The history of bad blood between Hamas and the Salafists dates back to 2007, when a Salafist group called the Army of Islam claimed responsibility for the kidnapping of BBC reporter Alan Johnston.
Hamas severed ties with the group and helped free Johnston after four months in captivity.
Tensions boiled over in August 2009, when Jund Ansar Allah (Soldiers of the Partisans of God) announced the creation of an Islamist "emirate" in Gaza, during a sermon at a mosque in the southern city of Rafah.
That prompted a furious response from Hamas, whose forces stormed the mosque, prompting clashes which left 24 people dead.
The Army of Islam also took part in the June 2006 kidnapping of Israeli soldier Gilad Shalit, who remains captive to this day.
These splinter groups are distinguished from other Palestinian movements including Islamists and closer to the ideology of Al-Qaeda, whose global jihadism is a departure from the Palestinian struggle against Israel.
Their actual links with Osama bin Laden's terror network appear tenuous, however, despite such concerns regularly expressed by the Israeli intelligence services.
This is largely thanks to the efforts of Palestinian leaders to prevent Al-Qaeda gaining a foothold on their territory.
Hamas denies an Al-Qaeda presence in Gaza, but has acknowledged that various groups are continuing "resistance to the occupation" and that it tries to exert control over them.