The video of Alan Johnston may be first shred of evidence that the kidnapped BBC Journalist is alive and well.

But it is also proof of a more alarming trend: the rise of Islamist groups in Gaza and the radicalisation of Palestinian society.

Before Mr Johnston's kidnapping, the Army of Islam was known as a minor Palestinian militant group, led by Mumtaz Dagmoush, the head of Gaza's most ruthless criminal families.

The Dagmoush clan is an old ally of Yasser Arafat's secular Fatah Party. The family's power was built on arms smuggling, extortion and crime. With thousands of heavily armed members, their influence reaches deep inside Palestinian society.

An offshoot of the militant Popular Resistance Committees – an umbrella group for fighters from various Palestinian factions – the group first surfaced in Gaza in June 2006 when it claimed responsibility for killing two Israeli soldiers at an Israeli military post near Gaza's southern Kerem Shalom crossing.

The Army of Islam was also among three groups that claimed responsibility for the abduction of Israeli Corporal Gilad Schalit last summer.

Mumtaz Dagmoush, the 28-year-old head of his family and leader of the Army of Islam, is notorious for his brutality, but his crimes were always understood as a way of build up his family's wealth and power:

His clan has staged previous kidnappings, but their victims were often released quickly in exchange for money or weapons from the Palestinian Authority.

So when Mr Johnston went missing 80 days ago, Dagmoush quickly became a prime suspect.

Last December, Hamas gunmen killed two Dagmoush clan members. When Hamas refused to turn over the victims' killers, Dagmoush vowed revenge.

Mr Johnston's abduction was initially seen as a way of pressuring Hamas. There were rumours the clan had demanded $5 million, the transfer of weapons and a tract of land.

But today’s video is further evidence the kidnappers demands are different: instead of money or guns, the group is pressing for the release of Abu Qatada, the radical Palestinian cleric, and other Muslim prisoners being held in British prisons.

Presumably echoing the rhetoric of his captors, Mr Johnston refers in the video to the British occupation of "Muslim lands" and condemns Britain's military presence in Iraq and Afghanistan.

Palestinian observers say Islamist tone of his message reflects a wider trend of al-Qaeda affiliated groups gaining strength in Gaza. With the collapse of authority in Gaza and its financial isolation, fundamentalist elements appear to be taking root.

In recent months, Islamist groups have attacked dozens of internet cafes, video shops and pharmacies which they claim, promote an "impure" Western lifestyle.

The Dagmoush family has apparently embraced al-Qaeda's ideology because it strikes a chord with some disenfranchised Palestinians who have grown increasingly frustrated with Western policies which they say have isolated their government, deprived them of wages and denied them decent lives.

A growing number of Palestinians are also disappointed with Hamas, the militant movement that swept to power last year on promises to rid government of corruption.

Instead, lawlessness has increased and life has deteriorated under international sanctions aimed at forcing the group to soften its stance towards Israel.

Meanwhile, some critics – including Dagmoush -- say Hamas has “sold out” by joining government, giving up the principal of "resistance" for power.

By borrowing al-Qaeda's ideology, they hope to present a more "pious" alternative, based on a radical interpretation of Islam borrowed from elsewhere.

Some Palestinian observers say the Army of Islam is simply using the jihadist message as a new tool in an old game: their constant struggle for power.

Most Palestinians are furious at the spread of their jihadist ideology, saying their legitimate struggle for statehood has been hijacked by criminals who use religion to justify common criminal acts for nothing more than personal gain.

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