Steps by Gaza's Hamas rulers to crack down on Salafist radicals have created tensions within the enclave that some fear may turn into an armed confrontation.
Although there are only a few hundred Salafists in Gaza, they have made a name for themselves as unafraid to openly challenge Hamas, seeking to outbid them in the fight against Israel and the defence of Islam.
Last year, Hamas launched a major crackdown on Salafist groups after several of them kidnapped and murdered an Italian peace activist whom they had seized as a hostage to demand the release of several of their fellow militants.
Earlier this week, a Gaza military court convicted four of them, with two getting life terms in jail.
In recent weeks, Salafist groups say they have come under renewed pressure from Hamas -- this time over Egyptian allegations they may have been involved in a deadly attack in northern Sinai in which 16 border police were shot dead.
"They have arrested and interrogated about 30 of our mujahedeen (fighters)," charged Abu Abdullah, who heads a Salafist group called the Mujahedeen Shura Council.
"Hamas is keeping the truce with the Jews while the enemy (Israel) is chasing mujahedeen day and night," he said in a statement sent to AFP.
"What hurts us is that people who call themselves Muslims in the internal security forces are pointing the dagger at the chest of the mujahedeen and won't stop their campaign against them," Abu Abdullah said.
"We don't fight other Muslims, but if we have to, we will defend ourselves and our mujahedeen," he warned.
Salafists are Sunni Muslims who promote a strict lifestyle based on the traditions of early "pious ancestors," and in Gaza they have made no secret of their disdain for Hamas over its observance of a tacit ceasefire with Israel and its failure to implement Islamic law.
Over the past few weeks, Salafist groups have fired rockets at southern Israel, and last week, hundreds marched through the southern border city of Rafah to protest against an anti-Islam film, waving Al-Qaeda flags.
"Hamas security is chasing mujahedeen who are targeting the enemy," agreed Abu Qatada al-Maqdisi of the Ansar al-Sunna group, who said the crackdown picked up speed after the attack on August 5.
"This campaign intensified after the attack in Egyptian Rafah."
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Within hours of the deadly attack, Egyptian security officials pointed the finger at militants from Gaza, with Cairo asking Hamas to provide information about several members of a Salafist group it believed was involved.
But Hamas has repeatedly insisted that no one from Gaza was involved in the attack, and denies there is any campaign under way to crack down on Salafist groups.
Interior ministry spokesman Islam Shawan says "a few" Salafists have been arrested, but only those involved in local security breaches.
"We only deal with those who break the law and breach security," he told AFP in an apparent reference to their rocket fire at Israel in defiance of the tacit truce observed by Hamas.
Salafist groups accuse Hamas of targeting them to curry favour with the administration of Egypt's new Islamist President Mohammed Morsi, whose Muslim Brotherhood shares ideological roots with Hamas.
"Egypt is pressuring Hamas to pursue Salafist groups, whether they were involved in the Sinai attack or not," said Mukhaimer Abu Saada, a political science expert at Gaza's Al Azhar University.
"Hamas feels the new Egypt is a supportive force that can be depended upon in the future, so it is keen to coordinate," he said.
Salafist groups, he said, embarrass Hamas with their rocket attacks on Israel and allegations that their militants were mistreated or tortured in custody.
"A clash between Hamas and Salafists is inevitable," he said.
But political analyst Mustafa al-Sawaf is not convinced that Hamas and the Salafists are on a collision course.
He doesn't think there is anything more than an "ideological" link between Salafist groups in Gaza and their counterparts in Sinai.
"There might be some joint activities like training, but this would be individually and not on the organisational level," he told AFP.
And for the moment, Hamas is trying to engage the Salafists "intellectually, although when things become difficult, they might use security measures."
But Abu Saada is sceptical that dialogue will bridge the yawning gaps between the two Islamist groups.
"Hamas might be able to succeed in reasoning with some groups, but not those that think it has deviated from resistance and Sharia," he said.