More than 100 people have died from landslides and flash floods set off by a tropical storm that blew across the south of the Philippines, police and disaster officials say.

The casualties, most of them inflicted late on Friday (local time), were all on the main southern island of Mindanao, they said.

"Many people were swept to the sea as floodwaters quickly rose due to the high tide," Manuel Luis Ochotorena, a disaster agency official, said.

"They never heeded the warnings. They thought it was a weak storm but it dumped more rains."

Ryan Cabus, an official in the town of Tubod, in Mindanao's north-west, said authorities were still trying to confirm reports a farming village had been buried by a mudslide.

He said power and communication lines to the area had been cut, complicating rescue efforts.

The weather bureau said the storm had gathered strength over the Sulu Sea and was packing winds of up 80 kilometres per hour and moving west at 20 kph.

It was heading out over the sea by midday on Saturday and would have moved clear of the Philippines by Monday, it said.

Rescuers evacuate residents from their homes during heavy flooding in Cagayan de Oro city in the Philippines. ( Reuters: Froilan Gallardo )

Emergency workers, soldiers, police and volunteers were being mobilised to search for survivors, clear debris, and restore power and communications.

More than 100 deaths were reported in various places, including 60 in Tubod, El Salvador and Munai towns in Lanao del Norte province.

In Zamboanga del Norte province, police said 42 people had been killed in the town of Sibuco and six in Salug.

Three people were killed in Bukidnon province, while politicians in Lanao del Sur province said 18 people had drowned in flash floods there.

Sixty-four people were reported missing in floods and landslides, according to a tally of reports form officials and police.

The Philippines is battered by about 20 typhoons every year, bringing death and destruction, usually to the poorest communities of the poor South East Asian country.

Last week, 46 people were killed in the central Philippines when a typhoon hit.

In 2013, super typhoon Haiyan killed nearly 8,000 people and left 200,000 families homeless.

Reuters/AP