Manila: Philippines President Rodrigo Duterte said on Saturday that IS militants were not behind the deadly attack at a casino in the capital Manila on Friday.
"That is not the work of ISIS," Duterte told reporters, using an acronym for IS.
IS claimed responsibility on Friday for the attack after Philippines officials said there was no evidence of militant involvement.
A top Philippines lawmaker said a gunman who stormed and torched a Manila casino, killing 36 people, was a "lone wolf" terrorist, contradicting the police assessment that the man had merely wanted to steal gambling chips.
The gunman, whose identity remains unknown, killed himself in a hotel room after being shot by security officers at the Resorts World Manila entertainment complex, authorities said.
Pantaleon Alvarez, speaker of the lower house of Congress and a close ally of President Rodrigo Duterte, said he was not convinced the incident was a criminal case of armed robbery and arson.
"This is a clear example of a 'lone wolf' terrorist attack targeting civilians to inflict maximum loss of life and damage to property, as what has happened in other countries," Alvarez said in a statement.
IS militants claimed responsibility for the attack, but this was dismissed by Philippines officials, who said it appeared to have been a botched robbery.
Duterte's spokesman, Ernesto Abella, said on Friday there was no proof linking the casino attack to a protracted urban battle between government troops and Islamist militants in the country's south. His security adviser, Hermogenes Esperon, said all the evidence pointed to an attempt to steal casino chips.
"We must draw up a clear and better plan to secure Metro Manila and other urban centres from IS-linked groups that we already know will attempt to kill and maim in pursuit of their jihadist ideology," Alvarez said.
The Philippines has been on heightened alert amid a crisis in the city of Marawi, on the southern island of Mindanao, where troops have been battling rebels since May 23 and martial law is in place.
Police and officials at Resorts World on Saturday released video clips from the casino CCTV for the first time since the attack in a bid to bolster their assertion that Friday's incident was a case of robbery.
Some of the CCTV footage showed a male, wearing dark clothes, bonnet and carrying a back pack, entering a mall leading to the casino through a parking area and bypassing a metal detector. A female security guard tried but failed to stop him, prompting people in that area to flee.
The CCTV also captured footage of the man firing shots at the ceiling, setting gaming tables and slot machines in flames, before forcing his way through a storage room where he appeared to be collecting and putting small boxes inside his back pack. Officials said the boxes contained casino chips.
"This is main reason why we showed this to you. He went inside the casino, the storage room, he stole 113 million (pesos) worth of chips and on his way out he was encountered by responding security team of resorts world and the police," Oscar Albayalde, chief of the Manila police, told a media briefing.
The stolen chips have been recovered.
"So until we get any indication (this) is a part of a terror attack or he is a member of any terror group we could not possibly say this is related to any terror attack," Albayalde said.
Police said on Saturday there were two "persons of interest" who have connections with the gunman and are cooperating with the investigation.
The attack at the casino hotel complex, which is close to an airport terminal and air force base, lasted more than six hours.
Security experts and patrons at the casino on Friday expressed alarm at the apparent ease with which a lone gunman was able to enter the building, open fire and start a blaze whose smoke killed more than 30 people.
Firefighters discovered the bodies in the main gaming area, hours after the country's police chief had said the situation was under control.
Police corrected earlier statements about the attacker.
They originally said he arrived at the hotel in a private car, but changed that to a cab, and they had described him as Caucasian and English-speaking but the cab driver told them he spoke in the local language.
"Our authorities should get their act together and put in place the highest level of security measures to prevent this from happening again, here or elsewhere in the country," Alvarez said.
"This incident should be a wake-up call for the police and the military to cooperate closely in making the seat of government and our financial and business centre safe from any terrorist attack."