Philippine authorities have begun mass burials for the hundreds of flash flood victims killed by a tropical storm that struck days before the island nation celebrates Christmas festivities, media reports said.

Government officials admitted that the number of casualties overwhelmed them, with the Philippine National Red Cross releasing estimates of more than 800 dead as of Monday night as more corpses were retrieved buried in mud or fished out from the sea.

Authorities fear that the number could easily breach the 1000 mark as hundreds were still reported missing and efforts to rescue survivors gradually shifted to retrieval operations as days wear on.

According to Benito Ramos, chief of the Philippines Office of Civil Defence, the latest dead count was pegged at 927 but he admitted that the number could run high soon as chaos that ensued following the weekend tragedy left officials grappling for order.

"We lost count of how many are missing," Ramos told the Associated Press.

His statement pretty much reflects the general situation on the ground, where survivors of the deadly flood were reportedly reduced to begging for food and water supplies in the initial hours following the disaster.

As evacuation sites were cramped with those who survived the horrific ordeal and some of their dead relatives, the stench of death started to pervade two of the most hardest hit cities, Iligan and Cagayan De Oro, both located far south of Manila.

Endless streams of dead bodies since Saturday prompted morgue keepers to close their doors while one funeral owner was forced to temporarily relocate unidentified bodies to a nearby garbage dump for later processing.

That move raised howl of protests among relatives trying to locate their missing loved ones, with scores calling the measures inhumane.

Iligan Mayor Lawrence Cruz insisted that burying the dead bodies in groups is the most logical solution available for them now.

"For public health purposes, we're doing this. The bodies are decomposing and there is no place where we can place them, not in an enclosed building, not in a gymnasium," Cruz was reported by AP as saying.

Cruz said that dead bodies were placed on plastic bags and were laid on temporary shallow graves for easy retrieval in the event that relatives will later come out to claim the flood victims.

Forensic experts reportedly extracted DNA samples from the dead bodies for proper identification later but it was unclear if the procedure was standard for all recovered corpses, media reports said.

By its latest assessment, the Office of Civil Defence has reported that some 143,000 people in 13 different locations in Southern Philippines were impacted by the disaster, with as many as 45,000 persons displaced when their homes were either damaged or swept way by the inundating waters.

According to UNICEF, many of the dead were women and children as reports indicated that whole families were carried by the raging waters in the dead night, catching almost everyone in their sleep.

Many more of these children were now orphaned or placed in evacuation centres, still wanting for essential supplies such as food, clothing and blankets, UNICEF said.