The death toll in the attack by a lone gunman who fired shots from an assault rifle and set fire to gambling tables in a Manila casino in the early hours of Friday morning rose to 37, reports said.

The victims, who did not appear to have been shot, are thought to have died of suffocation, CNN quoted Southern Police District Director Superintendent Tomas Apolinario as saying.

 "Most of the victims were women who were found dead inside the bathroom," he added.

Authorities said it was a robbery case and not a terrorist attack, despite ongoing ISIS-affiliated militant activity in the southern Philippines island of Mindanao. However, late Friday, ISIS claimed responsibility in a statement from its Amaq media wing, which said "Islamic State fighters" carried out the attack.

The tall, hooded gunman set fire to a VIP gaming room at Resorts World Manila, igniting a toxic blaze that killed the victims, including the assailant, said a Manila Times report.

The victims suffocated inside one of the main gambling venues, while dozens of other people were injured in a panicked crush to escape, police said.

The gunman committed suicide by setting himself on fire about five hours after storming the casino with an M4 assault rifle and a bottle of petrol that he used to start the fire, police chief Ronald Dela Rosa said.

Dela Rosa and other police officials said the assailant was not carrying out a terrorist attack as he did not shoot anyone. They said it appeared to be a bizarre robbery attempt by a “deranged” man.

“This is not an act of terror. There is no element of violence, threat or intimidation that leads to terrorism,” Dela Rosa told reporters.

Baker Atyani, a veteran journalist who has covered militant groups in the Philippines for two decades, said this was undoubtedly “a Daesh attack,” adding that it had issued an official statement claiming responsibility.

“They even named the attacker as Abul Kheir Al-Arkhebieli,” he told Arab News on Friday. “His aim was to inflict maximum damage and take as many lives as he could".