The death toll from Bopha, the strongest typhoon to have hit the Philippines this year has climbed to 647, authorities said Monday.

The National Disaster Risk Reduction and Management Council (NDRRMC) said that 1,482 people have been injured, while 780 people are still missing, Xinhua news agency reported. About 100 fishermen are feared lost between Mindanao and Indonesia's Sulawesi island, Reuters has reported.

The typhoon, which affected 5.4 million people in 30 provinces, mostly in central and southern Philippines, inflicted infrastructure damage worth 3.28 billion pesos ($84.99 million).

The agriculture department said the typhoon destroyed crops worth 8.6 billion pesos ($210 million), in southern Philippines.

Philippine President Benigno Aquino III has placed 50 areas in western, central, and southern Philippines under a state of calamity.

The Philippines' social welfare department and the U.N. have appealed for assistance even as humanitarian agencies are providing food, water, medicines, and shelter material for more than 5.4 million people affected by the storm.

Last week, the U.S. Deputy State Department spokesman Mark Toner said Washington offered its sympathies to the Philippines and Palau, which was also hit by the storm earlier in the week, and that both nations would receive assistance from the U.S.

"Our embassies in Manila and Koror have offered immediate disaster-relief assistance, and we are working closely with authorities in both countries to offer additional assistance as needed," Toner said in a statement.

Meanwhile, the Philippines government and Maoist rebels declared truce in two hard-hit southern provinces as the army is concentrating on relief operations and many rebels are recovering from the disaster, Reuters reported Monday quoting an army division commander.

"We heard the rebels had declared an informal ceasefire, we welcome that because we can all concentrate on helping typhoon victims," Major-General Ariel Bernardo told Reuters. "I believe many of these rebels were also affected and could be in the shelter areas."

Communist New People's Army (NPA) guerrillas are active in Davao Oriental province and Compostela Valley province, two worst-hit areas on southern Mindano Island.

About 20 typhoons hit the Philippines annually, often causing death and destruction. Last year’s Typhoon Washi killed 1,500 people.