REAL, Philippines - After days of wading through mud and floodwaters, exhausted Filipinos today scrambled for a seat on a rescue helicopter or ferry to escape coastal villages ravaged last week by back-to-back storms that killed at least 568 and left hundreds missing.

Philippine officials appealed for international aid after flash floods and mudslides swept away hundreds of houses, roads and bridges in what has been the southeast Asian nation's worst storm season in 13 years.

Food, clean water and medicine were in short supply - most shops and health centers were destroyed. People sifted through mud to salvage clothes and belongings. The dead were buried quickly to avoid disease.

In the town of General Nakar, the mayor asked for anti-venom drugs after a number of people were bitten by cobras, Social Welfare Secretary Corazon Soliman said.

With bulldozers still clearing piles of mud, uprooted trees, timber and debris from the roads, the only way out of the three worst-hit towns in Quezon province was on rescue helicopters or boats. The country's poorly equipped military struggled to provide aircraft and boats.

Washington offered to dispatch troops for humanitarian help and donated money and body bags. On Sunday, two HH-60 Pave Hawk helicopters from a nearby U.S. Navy ship delivered food aid and a team of experts.

Soliman said ships were unable to reach far-flung villages because of the floating debris. Instead, rubber boats ferried relief goods from ship to shore.

"People there are isolated. We don't know the number of dead there," Soliman said, adding that rescuers still hadn't been able to reach some villages, although relief goods had been air-dropped.

In Real, scores of people scrambled at a pier for a place on a ferry going to Manila. The ferry had a capacity of about 100 passengers, but it was soon overwhelmed by perhaps three times as many. The captain tried in vain to turn back the throng.

Jenny Martirez, who traveled with her husband and 1-year-old child, said their house in nearby Infanta town was buried under about 3 feet of mud.

"There is nothing there. No food, no water. All you can see is mud everywhere," she said.