A bloody rivalry has emerged between terrorist 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 Daesh-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 Daesh-affiliated group, was found near a beach in Mogadishu, it set off a hunt for suspected Daesh 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, Daesh's Al Naba newsletter noted deadly attacks on its fighters in Somalia and warned that "when the time of response comes from [Daesh], with God's will, we will be excused."

The Daesh-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.

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

"Al-Shabab miscalculated Daesh'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 Daesh-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 Daesh-linked militants, including foreign fighters, two Somali intelligence officials told AP. One suspected Daesh-linked fighter from Egypt was shot dead on Nov. 18 in Jilib.

As members of Daesh 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 Daesh-linked group has expanded its own assassination campaign. Daesh'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. Daesh-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.

Somali intelligence officials say al-Shabab's new manhunt is aimed at preventing the Daesh-linked terrorists 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.