Al-Qaeda in the Arabian Peninsula, classified by the United States as the network's deadliest franchise, "prohibits taking part in the fight against" IS, which controls swathes of both Iraq and Syria, AQAP said in a statement posted on jihadist forums.
"We urge all mujahedeen (Muslim fighters) to set aside their differences and inter-factional fighting and move instead against the crusade targeting all" jihadists, it added.
"We also urge all Muslims to back their brethren, with their souls, money and tongues, against the crusaders."
"This is a campaign against Islam" that has brought together "crusaders (Christians), majus (a pejorative term for Iranians), and traitor apostate leaders," it said.
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