A bloody rivalry has emerged between extremist groups in Somalia as the al-Qaida-linked al-Shabab hunts upstart fighters allied to the Islamic State group, who have begun demanding protection payments from major businesses, officials tell The Associated Press.

The rivalry supports some observers' suspicions that al-Shabab, now scrambling to defend its monopoly on the mafia-style extortion racket that funds its high-profile attacks, is drifting from its long-declared goal of establishing a strict Islamic state.

The manhunt began in October with the killing of a top leader of the IS-linked group by a suspected al-Shabab death squad in the capital, Mogadishu, according to several Somali intelligence officials, who spoke on condition of anonymity because they were not authorized to speak to the media.

When the body of Mahad Maalin, deputy leader of the IS-affiliated group, was found near a beach in Mogadishu, it set off a hunt for suspected IS sympathizers within al-Shabab's ranks, officials said. Maalin had been suspected of trying to extend his group's reach into the capital.

Last month, the Islamic State group's Al Naba newsletter noted deadly attacks on its fighters in Somalia and warned that "when the time of response comes from the Islamic State, with God's will, we will be excused."

The IS-affiliated group in Somalia, largely made up of al-Shabab defectors, first announced its presence in 2016 with attacks in the far north, far from Mogadishu and most al-Shabab strongholds. Though estimated at a few hundred fighters at most, their emergence in one of the world's most unstable countries has been alarming enough that the U.S. military began targeting it with airstrikes a year ago.

While al-Shabab and its thousands of fighters have hunted down suspected IS sympathizers before, they had not taken the young group's expansion seriously until now, observers say.

"Al-Shabab miscalculated IS's organizational capability and ambitions to extend its reach beyond the north, having judged it by its handful of fighters there, and thus missed the bigger picture," said Mohamed Sheikh Abdi, a Mogadishu-based political analyst.

The revelation by businessmen that IS-linked operatives had begun making extortion demands took al-Shabab's leadership by surprise, prompting the manhunt that has led to assassinations and the detention of over 50 suspected IS-linked extremists, including foreign fighters, two Somali intelligence officials told AP. One suspected IS-linked fighter from Egypt was shot dead on Nov. 18 in Jilib.

As members of the Islamic State group flee shrinking strongholds in Iraq and Syria, fears have grown that the fighters will find a new and welcome home in parts of Africa.

Alarmed by al-Shabab's deadly attacks, the IS-linked group has expanded its own assassination campaign. IS's Amaq news agency, turning its attention to the young affiliate, has released videos showing what it called killings by the group's death squad.

IS-linked fighters already had claimed responsibility for 50 assassinations in southern Somalia between October 2017 and August, often against federal government officials, according to a report released last month by the United Nations panel of experts monitoring sanctions on the country.

While extortion is the fighters' latest tactic it is nothing new in Somalia, where al-Shabab has long used death threats and other intimidation to pressure businesses to pay what is called "zakah," or charity. The money is their main source of funding. "Indeed, al-Shabab is likely generating a significant budgetary surplus," the U.N. panel of experts said, noting that one of its checkpoints brought in about $10 million a year.

With no strong government to protect them, businessmen often say they have no choice but to pay in exchange for protection.

Among the companies targeted by suspected IS-linked extremists is Somalia's telecom giant, Hormuud, which intelligence officials say has lost up to 10 employees in attacks in recent weeks. Hormuud officials did not respond to requests for comment.

Businesses worry that the rise of another extremist group seeking cash, as well as a new effort by Somalia's central government to impose taxes, will bleed them dry.

"At this point, (businesses) are faced with two equally undesirable alternatives," said Abdisamad Barre, a professor of business management in Mogadishu. "Rejection to the demands for extortion will pave way for attacks by IS, and paying them to evade danger will anger al-Shabab."

Somali intelligence officials say al-Shabab's new manhunt is aimed at preventing the IS-linked extremists from expanding their extortion demands into southern Somalia, where al-Shabab levies millions of dollars in taxes per year on travelers and cargo meant for the lucrative port of Kismayo.

Another al-Shabab tactic against its young rival is pressuring religious leaders to issue a fatwa, or edict, declaring the IS group "un-Islamic," thus legitimizing a war against them, according to sources close to al-Shabab who requested anonymity for fear of reprisal.

Security experts, however, say al-Shabab will find it difficult to unearth IS supporters even within its own ranks.

"That will be a major challenge," one official said, noting that IS-linked loyalists could be waiting quietly even in al-Shabab's leadership to make a move. "But that will probably take a long time given al-Shabab's vigilance."

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Associated Press writers Maamoun Youssef in Cairo and Cara Anna in Johannesburg contributed.

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