MOGADISHU, Somalia -- A renegade leader of Somalia's Islamic extremist insurgents, al-Shabab, has surrendered to the government.

Mukhtar Robow was flown to Mogadishu Sunday from Hudur in southwestern Somalia, said Col. Adam Ahmed, a senior Somali police official. Robow was earlier airlifted from the Bakool jungle area where he and hundreds of his militia have been fighting al-Shabab since early last week.

Robow had fallen out with the al-Shabab leadership, which has been carrying out a purge of its ranks. The action against al-Shabab leaders was started by al-Shabab leader Ahmed Abdi Godane who started to kill his rivals. Among those killed was the rapping American Jihadist, Omar Hammami and Ibrahim Afghani, one of the group's founders and others. Godane was killed in a U.S. airstrike in 2014.

Robow's defection comes after the United States in June cancelled a $5 million reward offered for his capture. His surrender is the culmination of months of negotiations and it is believed the cancellation of the bounty for his capture helped convince Robow to give himself up to the Somalia government.

Robow, who was the deputy director of al-Shabab, is the highest official to have ever quit the group. Estimated to be in his 50s, Robow is one of al-Shabab's most experienced leaders, having travelled to Afghanistan and trained alongside al-Qaida around 2000 after studies in Sudan. He had served as an al-Shabab spokesman, military commander and spiritual leader who planned and executed deadly attacks on Somali government troops and African Union peacekeeping forces, according to the U.S. Rewards for Justice program.

Already under house arrest in Mogadishu is the former spiritual al-Shabab leader Sheikh Hassan Dahir Aweys. Aweys also defected to the government because of the purge within al-Shabab.

Al-Shabab last year was named the deadliest Islamic extremist group in Africa, with more than 4,200 people killed in 2016, according to the Washington-based Africa Center for Strategic Studies.

The extremist group has vowed to step up attacks after the recently elected government of President Mohamed Abdullahi "Farmajo" Mohamed launched a new military offensive against it. The group also faces a new military push from the United States after President Donald Trump approved expanded operations, including airstrikes. Al-Shabab still controls parts of rural Somalia.