President Rodrigo Duterte has asked Congress to extend martial law in Mindanao, saying he "has come to the conclusion" that the rebellion in southern Philippines will not be quelled by government troops by July 22, the end of the 60-day period.

Duterte justified his request in a letter sent to Congress on Tuesday, saying "a lot more" has to be done to bring back order and safety in Mindanao.

"Despite the progress and significant strides that we have achieved against the DIWM (Da’watul Islamiya Waiiyatul Masriq) and its sympathizers, however, the rebellion persists and a lot more remains to be done to completely quell the same and bring back public order and safety in Mindanao," the President said in the letter.

Duterte also cited as reason the presence of foreign terrorists which he claims is supporting local terrorists as well as the presence of other local terrorist groups apart from the Maute.

"Other Islamic State-inclined armed groups ASG (Abu Sayyaf Group), AKP (Ansar al-Khalifah Philippines), and BIFF (Bangsamoro Islamic Freedom Fighters) which are capable of perpetrating atrocities and violent attacks against vulnerable targets, remain scattered in various areas in Mindanao," he said.

The President also lamented the "cruelty" of the ongoing firefight between state forces and Maute extremists.

"…The crisis in Marawi City has introduced a newly evolving type of urban warfare- one that is characterized by the rebels’ total disregard for civilian lives, cruelty to combatant and non-combatants alike, and widespread looting and pillaging of occupied communities," he said.

Duterte placed the entire island of Mindanao under military rule last May 23 after clashes between state forces and Maute extremists erupted in the Islamic City of Marawi.

Congress will convene on Saturday to discuss Duterte's request of extension until December 31, 2017.

Under the Constitution, the President may declare martial law for a a period not exceeding 60 days in case of invasion or rebellion, and when public safety requires it.

The Constitution, however, also states that “upon the initiative of the President, the Congress may, in the same manner, extend such proclamation or suspension for a period to be determined by the Congress, if the invasion or rebellion shall persist and public safety requires it.”

Here is the full letter of the President:

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