MANILA (UPDATE) - President Rodrigo Duterte has called on Congress to extend martial law in Mindanao until the end of the year, Malacañang said Tuesday.

Presidential Spokesperson Ernesto Abella said Duterte has decided to ask Congress for the extension since “he has come to the conclusion” that the siege in Marawi City would not reach its end by July 22, the deadline for the 60-day period of the martial law proclamation.

"For this reason, that because public safety requires it, I call upon the Congress to extend until 31st of December 2017, or for such a period of time as the Congress may determine, the proclamation of martial law and the suspension of the privilege of the writ of habeas corpus in the whole of Mindanao," said Duterte in a statement, as delivered by Abella.

Duterte on Monday evening sent to Congress a 7-page letter which comes with a detailed report justifying the need for an extension. The President has also called for a joint session of Congress on July 22 for lawmakers to tackle the extension request.

Abella said Duterte asked for the martial law extension to allow government troops to deal with the Marawi crisis “unhampered by deadlines” and focus on rebuilding the city.

Duterte’s decision to seek a martial law extension until the end of the year is contrary to Senate President Aquilino Pimentel III’s pronouncement Monday evening that the President only asked for an extension of another 60 days.

Abella said, the President’s mind may have changed from the time he told Pimentel he would only seek a 60-day extension.

“The president has his own sources of information that prompted him to come to this conclusion, and I’m sure all of these things is all related towards ensuring public safety,” Abella said.

Duterte placed the entire Mindanao under martial law on May 23 after the Islamic State-linked Maute and Abu Sayyaf groups laid siege on Marawi City in a bid to establish an ISIS province in the Philippines.

The long-drawn conflict in Marawi, considered one of the most important Islamic cities in the predominantly Catholic Philippines, has left at least 556 dead, most of whom were terrorists.

The emergence of groups pledging allegiance to Islamic State has been considered the biggest security problem to face the year-old Duterte administration.

The rise of pro-ISIS groups in the country has also raised alarm in Washington and the Philippines’ neighbors in the region, which fear that the notorious terror group was seeking to establish a new front in Asia amid its successive losses in Iraq and Syria.