Thirty-seven people were believed killed in a fire that engulfed a shopping mall in the southern Philippine city of Davao, local authorities said on Sunday.

A Bureau of Fire Protection commander at the scene said the chances of the 37 surviving were "zero", Paolo Duterte, Davao's vice mayor, who is also the president's son, wrote in a Facebook post.

The blaze started at the four-storey NCCC Mall on Saturday morning and people were trapped inside, including at a call centre on the top floor, Ralph Canoy, a police officer in the district, told AFP.

Canoy said the fire was still going before dawn on Sunday morning, nearly 24 hours later.

"The fire started on the third floor, which houses products like fabrics, wooden furniture and plastic ware, so the fire quickly spread and it's taking a long time to put out," he said.

He said investigators believed some of those likely killed had been trapped in the call centre, which operated 24 hours a day.

"It's possible that while they were working, they did not immediately notice the fire spreading," Canoy said of the call centre workers.

He said the reason for the blaze was not immediately known.

President Rodrigo Duterte, who served as mayor of Davao for about two decades and continues to live in the city, visited the mall on Saturday night to comfort relatives of the victims, one of his aides told AFP.

Davao, with a population of about 1.5 million people, is the biggest city in the southern Philippines. It is about 1,000 kilometres (600 miles) south of Manila, the nation's capital.

The fire adds more misery to the mainly Catholic Philippines at Christmas, with a tropical storm killing at least 182 people and displacing tens of thousands of others in recent days.

Many of those killed in the storm were also in the southern region of Mindanao.

Deadly blazes occur regularly in the Philippines, particularly in slum areas where there are virtually no fire safety standards.

There have also been horrific fires in bigger buildings and factories, where corruption and exploitation mean supposedly strict standards are often not enforced.

Seventy-two people were killed in 2015 when a fire tore through a footwear factory in Manila. Survivors of that blaze blamed barred windows and other sweatshop conditions for trapping people inside the factory.

In the deadliest fire in the Philippines in recent times, 162 people were killed in a huge blaze that gutted a Manila disco in 1996.