AFP/Manila

Heavy rains pummelled the entire Philippines on Saturday, flooding more areas as the government declared a "state of national calamity".

The death toll after a week of devastating weather has risen to 41, according to confirmed reports from national and local disaster monitoring agencies.

Poor farming communities in the main southern island of Mindanao were flooded Saturday after at least two rivers burst their banks, local disaster officials said.

The storm, locally named Onyok, had weakened into a low pressure area after hitting land late Friday but continued to bring more rains to Mindanao and the central Visayas islands.

Cold monsoon winds blowing from the northeast brought rains to Luzon, the main northern island, where large farming communities have been submerged in mostly waist-deep floods from Typhoon Melor, which hit at the start of the week.

Areas inundated by Melor have barely recovered from floods brought by Typhoon Koppu in October.

"Almost the entire Philippines is experiencing rains. More floods are possible," state weather forecaster Robert Badrina told AFP.

"We expect the rains to peak today. The weather will start to improve tomorrow," he said.

President Benigno Aquino ordered state agencies to "hasten the rescue recovery, relief and rehabilitation efforts," in a statement declaring a state of "national calamity".

The government will control prices of basic goods in affected areas, the statement read.

The weather bureau issued a warning of up to 30 millimetres of rain per hour in the central islands of Cebu, Negros and Bohol, while residents were advised to be on alert for possible evacuation.

The three Visayas islands, with a combined population of 7.4 million people, are home to major tourism, trading and agricultural hubs.

Close to 10,000 people were evacuated from the poor farming region of Caraga in Mindanao before the latest storm.

In Agusan del Sur province, large portions of the national highway were inundated after a nearby river burst its banks, regional civil defence officer Manuel Ochotorena told AFP.

Another river in Davao del Norte province, roughly 100 kilometres (62 miles) away, also burst its banks, forcing residents out of their homes, provincial disaster officer Romulo Tagalo said.

In Luzon, 140,000 people displaced by floods and landslides triggered by Melor remained in evacuation centres.

The Philippines, a nation of 100 million, is battered by an average of 20 typhoons per year, many of them deadly.

In 2013, Super Typhoon Haiyan wiped out entire fishing communities in the central islands, leaving 7,350 people dead or missing.