Aid agencies say the situation after Typhoon Bopha in the Philippines is getting worse, with the death toll climbing to 540.
More than 800 people are still missing, including hundreds of fisherman. Families and fishing companies reported losing contact with more than 300 fishermen at sea, government officials said on Sunday.
The fishermen from southern General Santos city and nearby Sarangani province left a few days before Bopha hit the main southern island of Mindanao on Tuesday, causing deadly flash floods, Benito Ramos, civil defence chief, said on Sunday.
Ramos said the fishermen were headed to the Spratly Islands in the South China Sea and to the Pacific Ocean. He said there has been no contact from them for a week.
"We have declared them missing," he said. "Maybe they are still alive."
Ramos said they may have sought shelter on the many small islands in the Spratlys and the Celebes Sea, and lost battery power and have not been able to call.
He said the coast guard, navy and fishing vessels have launched a search.
Rescuers continued searching for bodies or signs of life under tonnes of fallen trees and boulders in the worst-hit town of New Bataan, where rocks, mud and other rubble destroyed landmarks, making it doubly difficult to search places where houses once stood.
Hundreds of refugees, rescuers and aid workers took a break on Sunday to watch the Manny Pacquiao-Juan Manuel Marquez fight on a big TV screen, only to be dismayed by their hero's sixth-round knockout.
Nearly 400,000 people, mostly from Compostela Valley and nearby Davao Oriental province, have lost their homes and are crowded inside evacuation centers or staying with relatives.
Benigno Aquino III, the Philippine president, declared a state of national calamity on Friday, which allows for price controls on basic commodities in typhoon-affected areas and the quick release of emergency funds.
Officials said on Sunday that 316 people were killed in Compostela Valley, including 165 in New Bataan, and 301 in Davao Oriental.
More than 45 people were killed elsewhere. Nearly 900 are missing, including the fishermen and 440 from New Bataan alone.
After hitting the southern Philippines, Bopha moved out to sea but then veered back towards the country's northwest on Saturday, prompting worries of more devastation.
As of late Sunday, however, it had begun to dissipate and weaken into a low-pressure area as it moved farther into the South China Sea, about 105km west of the Philippines' Ilocos Norte province.