Mahmud, 39, is believed to be holed up in Marawi City, where the Philippine army is battling the extremist Maute group, which has seen 44 people, including two Malaysians, killed.
President Duterte expressed confidence that the government will win the war against the forces of the ISIS-backed Maute Group and the Abu Sayyaf Group now ongoing in Marawi City.
The violence prompted President Rodrigo Duterte to declare martial law in the country's south, where a Muslim rebellion has raged for decades.
He said Hapilon suffered a stroke after a government airstrike wounded him in January.
"In as much as we would like to avoid collateral damage, these rebels are forcing the hand of government by hiding and holding out inside private homes, government building and other facilities", Padilla said.
Clinton joined many people on social media on Saturday to criticise Duterte, who has also carried out a war on drugs that has left thousands of people dead and rights groups say may be a crime against humanity.
"I will handle the rest", Duterte said, according to a Friday report from Channel NewsAsia.
Ano predicted that the military operation will take about a week as soldiers go house to house to clear the city of militants.More news: English Premier League winners Chelsea cancel victory parade
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Indonesians and Malaysians are among foreign jihadists fighting the Philippine army in Mindanao island, Manila's solicitor-general said today, in a rare admission that outsiders are collaborating with domestic Islamist groups. "We were sure they would get to us", he said.
In a sign of the confusion over events inside the city, a local police chief told the AP on Friday that he was fine - two days after Duterte told journalists the police chief had been beheaded by militants. In 2014, Hapilon pledged allegiance to ISIS. He also heads an alliance of at least 10 smaller militant groups, including the Maute, which has a presence in Marawi and was instrumental in fighting off government forces in this week's battles.
"The events commencing on 23 May 2017 put on public display the groups' clear intention to establish an Islamic state and their capability to deprive the duly constituted authorities - the President foremost - of their powers and prerogatives", the report said.
Washington has offered a $5 million reward for information leading to Hapilon's capture, but he has proved elusive. It is one of a number of hardline groups that split from the nation's biggest Muslim rebel organisation in anger at a planned peace accord.
The Chief Executive also said he would take full responsibility for the outcome of martial law in Mindanao. "The local groups have transformed".
Ms. Sereno, who obtained her undergraduate degree in economics at the Ateneo de Manila University, maintained that the Constitution "absolutely prohibits" the kind of martial law that the former President Ferdinand E. Marcos declared in September 1972.
Duterte had repeatedly threatened to place the region under martial law, which allows him to use the armed forces to carry out arrests, searches and detentions more rapidly.