Iligan, Philippines:

Muslim extremists have staged a daring jailbreak in the southern Philippines, freeing 28 detainees in the latest in a series of mass escapes, officials said on Sunday.

About 50 heavily armed members of the Maute group, which has pledged allegiance to the Islamic State group, raided the local jail in the southern city of Marawi on Saturday, freeing eight comrades who were arrested barely a week ago, police said.

Twenty other detainees, held for other offences, also escaped in the raid, provincial police chief Senior Superintendent Agustine Tello said.

The freed members of the Maute group were arrested on August 22 after soldiers manning an army checkpoint found improvised bombs and pistols in the van they were driving.

The Maute group is one of several Muslim gangs in the southern region of Mindanao, the ancestral homeland of the Muslim minority in the largely Catholic Philippines.

The group has carried out kidnappings and bombings and is believed to have led an attack on an army outpost in the Mindanao town of Butig in February.

The fighting there lasted a week, leaving numerous fatalities and forcing tens of thousands to flee their homes as helicopter gunships fought off the attackers.

During the Butig fighting the group’s members were seen carrying black flags of the Islamic State group, and bandanas bearing the jihadists’ insignia were found in their base, the military said.

Authorities said they were investigating why the jail’s guards did not resist Saturday’s raid or why security had not been increased after high-risk suspects were brought in.

The jailbreak is just the latest mass escape from poorly secured Philippine jails, with the incidents often involving Muslim extremists.

In 2009, more than 100 armed men raided a jail in the strife-torn southern island of Basilan, freeing 31 prisoners, including several Muslim guerrillas.

The southern Philippines has been plagued by a Muslim separatist insurgency for over four decades, with the conflict leaving more than 120,000 dead.

President Rodrigo Duterte has been pursuing peace talks with the larger, more established Muslim insurgent groups, the Moro National Liberation Front and the Moro Islamic Liberation Front. Ceasefires with these groups are still in force.

However the smaller groups like the Maute group and the Abu Sayyaf group, are not covered by the ceasefires and are not part of the peace process.