MANILA — The death doll from the flooding unleashed by heavy rains on Christmas Day rose to 25 on Wednesday, the Office of Civil Defense (OCD) said.

Sixteen of the reported deaths were from Northern Mindanao, said OCD information officer Diego Mariano. Five fatalities were tallied in the Bicol Region, while Eastern Visayas and Zamboanga Peninsula recorded 2 deaths each, Mariano added.

The official said another 26 people, mostly fishermen, remain missing after the flooding.

Twelve of the missing persons were from Bicol, while 11 were from Eastern Visayas. Two remain missing in Northern Mindanao, while 1 more missing individual was from Zamboanga Peninsula.

Search and rescue operations for them are ongoing, Mariano told ABS-CBN's TeleRadyo.

Nine people were also injured due to the bad weather, he said.

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The heavy rains damaged some P63.8 million worth of crops, while the cost of damage to infrastructure was pegged at around P20.8 million, Mariano said.

In a statement, the National Disaster Risk Reduction and Management Council (NDRRMC) said relief efforts were under way to help people in areas hit hard by the flooding, as more than 81,000 people sheltered in evacuation centers.

Officials on Wednesday were to conduct aerial surveillance over Misamis Occidental to assess the extent of the damage.

The heavy rains were caused by a shear line or area where warm and cold air meet, forming rain clouds, the state weather bureau earlier said.

The weather turned bad as the disaster-prone nation of 110 million people prepared for a long Christmas holiday. Millions of people travel to their hometowns for family reunions during this period.

The state weather forecaster said moderate to heavy rains were likely across southern and central regions on Wednesday and Thursday due to a low pressure area off the coast that could develop into a tropical depression.

"Flooding and rain-induced landslides are likely, especially in areas that are highly or very highly susceptible to these hazards," the weather bureau said.

The Philippines is ranked among the most vulnerable nations to the impacts of climate change.

Scientists have warned that storms are becoming more powerful as the world gets warmer.

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— With a report from Agence France-Presse