Philippine armed forces on Monday relaunched a military intervention against so-called "Islamic State" (IS)-allied militants in the southern city of Marawi following a brief "humanitarian pause" to mark the Islamic holiday Eid al-Fitr.

"Our offensive operations have resumed and will continue so we can liberate Marawi City at the soonest time possible," said army spokesman Lieutenant Colonel Jo-ar Herrera. "We are focused and committed, and we will accomplish our mission."

Philippine authorities believe the militant uprising is "crumbling" after several leaders reportedly fled the area, including Isnilon Hapilon, the Abu Sayyaf militant group's leader.

Read more: Southern Filipinos caught between violence and a humanitarian crisis

"We have validated reports that there are leadership problems inside," Herrera said. "They also lack ammunition, have very limited maneuver space and their defensive position is getting small, too."

The militant uprising erupted in May in response to a raid by Philippine forces that failed to capture Abu Sayyaf chief Hapilon. Following the raid, the Maute group, a loose collective of IS-allied militants, launched an assault on the city resulting in its capture.

Human rights concerns

The uprising prompted Philippine President Rodrigo Duterte to declare martial law on the southern island of Mindanao. Human rights organizations have criticized the president's move, saying it could lead to large-scale abuses by the armed forces

"Duterte's martial law threatens military abuses in Mindanao that could rival the murderous 'drug war' in urban areas," said Phelim Kine, Human Rights Watch's deputy Asia director.

Upon taking office in June last year, Duterte launched a brutal campaign against suspected drug traffickers, peddlers and users; more than 7,000 people have died since.

Read more: Will the ICC prosecute Philippine President Rodrigo Duterte?

"It's crucial that the country security forces abide by international law at all times and hold rights violators to account," Kine added.

The month-long conflict between Islamist militants and government forces has claimed more than 380 lives and displaced an estimated 300,000 people.

ls/msh (dpa, EFE)