MANILA - Welfare workers say they are tracking the whereabouts of potentially hundreds of children who lost their parents in devastating weekend floods that submerged most of the Philippine capital.

And there was growing concern the new orphans could be driven out on to the streets, joining hundreds of thousands of other children who are fending for themselves in cities across this impoverished Southeast Asian nation.

Poor communities living in hazard-prone slums along riverbanks bore the brunt of devastation when six-metre (20-feet) floodwaters unleashed by tropical storm Ketsana swamped Manila and surrounding regions on Saturday.

The disaster claimed at least 277 lives, according to the official toll, although that number is expected to rise as authorities establish a clearer picture of the carnage.

Natalie Lamin, child protection chief of the United Nations Children's Fund (UNICEF) office in the Philippines, said her organisation was working to quickly determine how many children were orphaned by the deadly floods.

"We hope to be able to establish a database by next week," she told AFP.

More than 200 volunteers are now trying to track down the orphans, who may have sought refuge in the hundreds of shelters set up in schools and other public buildings around Manila, Lamin said.

The child protection agency is working in partnership with the Philippine government's social welfare department.

Brothers Roderick and Michael Luces, aged 17 and 19 respectively, have been left to rely on donated clothes from classmates and food handouts after losing both their parents and four of their siblings on Saturday.

The family was washed away by the rising waters of a river in the city's Bagong Silangan district. The brothers have since been living with thousands of other people at a local gymnasium turned into an evacuation centre.

"Everything was swept away. We don't have any money. We're just begging for food here," said their 25 year-old sister, Agnes, who is married with two children of her own.

"I guess they will have to stay with me."

Orphaned children had the best chance of avoiding a life on the street if they remained in the same community, preferably under the care of relatives or even neighbours, Lamin said.

When neither is available, it is only then that social welfare services ought to look at other options, she added.

"Being in a community adds an extra layer of protection if a family or a community is looking after their children," Lamin said.