Bandleader Jamal Al-Bayouk said he and his musicians would not risk performing in the southern Gaza Strip any more after militant Islamists threatened to kill them at a wedding party.

They had just finished performing east of Khan Younis when armed militants burst in, set fire to $40,000 worth of instruments and fired shots between the legs of band members.

"One gunman told another: Don't shoot between the legs. Shoot at the legs!" Bayouk told Reuters.

"Another told me: Prepare for death, you immoral infidel," the 49-year-old man said, at the Gaza shop where he fixes musical instruments and rents sound systems.

He said several other singers and members of bands had been beaten up by al-Qaeda style jihadists who disapprove of their music and added that in his opinion there could be further attacks as summer begins and people hold weddings and parties.

"I am afraid and I am not optimistic but I will continue because there are 20 families depending on my profession," Bayouk said.

The threat comes from Salafi jihadists whose agenda of global holy war against the West is against the nationalist goals of Gaza's rulers Hamas, an Islamist movement which denies seeking to create a theocracy in the enclave.

While seen in Israel as a dangerously fundamentalist Palestinian enemy force, Hamas is not Islamist enough in the eyes of hardline groups which have stepped up attacks in the Gaza Strip over the past several months, targeting Hamas security men and offices.

Hamas accuses them of attacking wedding parties, Christian sites, internet cafes and women's hair dressing salons. The groups deny the accusations.

SUMMER DAYS

Last Sunday, masked gunmen vandalised a U.N.-run summer camp for children after Islamist militants accused the United Nations of promoting immorality among Gaza's Muslim youth.

Ehab al-Ghsain, spokesman of the Hamas interior ministry, said security services had finalised the plan to provide security protection to public places where residents would go to enjoy summer holidays including restaurants and beaches.

He said a number of suspects were detained over the attack on the UN summer camp, but gave no details of their affiliation.

Ghsain attributed a drop in bomb attacks in the territory to a security campaign to "arrest characters involved in causing chaos" and to an educational plan to rehabilitate members.

Hamas wrested control of Gaza from Palestinian President Mahmoud Abbas's secular Fatah movement in fighting in 2007.

The enclave is under an Israeli-led blockade. The West shuns Hamas over its refusal to recognise Israel, renounce violence and accept existing interim Israeli-Palestinian peace deals.

Analysts and rival officials say groups inspired by al Qaeda pose a clear challenge to Hamas rule in Gaza.

They say Hamas is reaping the harvest it sowed: many current members of the Jihadist Salafi factions were once trained activists of Hamas' armed wing, Izz el-Deen Al-Qassam Brigades.

Believers in al Qaeda ideology may number in the hundreds or thousands, say analysts. But Ghsain insists there a no more than a few dozen.

Political analyst Talal Okal says the number is rising, thanks to the Islamist environment Hamas encourages.

"The growing number of those extremist groups may have a bad impact on Hamas," Okal said.

Salafis criticise Hamas for taking up government in the first place. They accuse the movement of failing to implement Islamic law in favour of having relations with Western countries they denounce as "crusaders and infidels".

Ahmed Assaf, a spokesman for Palestinian President Mahmoud Abbas' Fatah movement, said Hamas's bid to portray itself as the only true Muslim movement had obviously backfired.

"Hamas raised its members in the belief that Fatah and other non-Hamas parties were secular and infidels and now Hamas is suffering from its own incitement," Assaf said.

"Hamas now finds itself in the same position. It is governing by secular law and preventing resistance against Israel from Gaza. That has prompted many shocked members of Qassam to abandon the group and join the more extreme Islamist cells," Assaf said.

Boaz Ganor, an Israeli expert in counter-terrorism, said the stronger those groups become the bigger threat to Hamas rule they would pose. The more willingness Hamas showed towards getting international legitimacy and opening to the West, the more vocal those groups would become.

"To have an element that does not obey the new Hamas guidelines and policy, an element that endorses global Jihad, is counterproductive to the Hamas approach towards the international community," Ganor said by telephone from Israel.

Okal said Hamas would not allow them to cross the red line.

"We all saw how Hamas intervened militarily and strongly when one group defied them and tried to announce an emirate of their own in Gaza," said Okal, referring to a battle in which 28 people were killed in addition to six Hamas policemen.

Ganor said the hardline groups were lose cannons in territory Hamas controls, and as far as Israel was concerned it is Hamas that bears responsibility for their actions.

"If Hamas would be seen as turning a blind eye to or cooperating with those elements, this is going to cause a great loss to Hamas," Ganor said.