The U.S. military trucked in supplies and marshaled helicopters and Navy ships as the Philippines struggled with the aftermath of back-to-back storms that have left more than 600 dead.

After pulling six people from landslides late Thursday and early Friday, Filipino rescuers said they remained hopeful of locating more survivors in the stricken north of the country, but retrieved only bodies on Saturday.

With roads blocked and bridges washed away, the Philippine government's resources have been stretched thin. Officials have asked U.S. troops in the country for an annual military exercise to extend relief operations.

Troops from the 31st Marine Expeditionary Unit, based in Okinawa, Japan, had just finished rescue and cleanup work around the Manila, which experienced the worst flooding in over four decades after Tropical Storm Ketsana dumped record rains Sept. 26. That disaster displaced about 1 million people and killed 337 in the capital and surrounding provinces. More than 287,000 remain in evacuation centers.

Then Typhoon Parma struck Oct. 3 and has lingered as a tropical depression for about a week, also over the main northern Philippine island of Luzon. It has dumped more heavy rains, triggering floods and landslides that have killed at least 276 people, most of them in the last two days. It has displaced about 170,000 people.

Regional civil defense official Olive Luces said 152 bodies have so far been recovered in Benguet province — 125 miles (200 kilometers) north of Manila — 23 in Mountain Province, and 50 in Baguio city. Some 51 deaths have been recorded earlier in eight other provinces.

Marine Capt. Jorge Escatell, a U.S. military spokesman, said troops have trucked tons of U.N. food aid from Manila to a Philippine military camp in northern Tarlac province for distribution by the Americans on Sunday to victims of Typhoon Parma.

Marine CH-46 helicopters have also flown over the flooded region to assess the damage and find locations for a medical mission and food distribution. Heavy equipment also will be brought in to help clear roads littered with debris, Escatell said.

Also, about 200 U.S. Marines and sailors are on standby to help in the relief mission. They are aboard two Navy ships, USS Harpers Ferry and the USS Tortuga, off Pangasinan province, and in a Philippine military camp just south of the Cordillera mountains on Luzon.

Escatell said the U.S. troops were weary but still enthusiastic for their humanitarian mission.

"This is what we trained for," he said. "We are tired ... but it's well worth it, especially when you see the smile on the children's faces when we come to people that need medical attention or just need some kind of support."

Rescuers are still searching landslides for survivors. Among the six pulled out alive on Thursday and Friday was a 17-year-old boy who was buried in his home in Baguio city. Five others were found in Mountain Province, Luces said.

More bodies were pulled from under tons of mud and rocks Saturday, but no survivors, she said.

Benguet Gov. Nestor Fongwan told ABS-CBN television his province needed more embalmers and caskets for the large number of dead.

Mayor Artemio Galwan of La Trinidad township in Benguet province said at least 78 bodies have been recovered there. He appealed for shovels and other tools as well as portable spotlights to allow volunteers to continue digging at night.

Luces said, "We are hopeful that we will get more people alive."

With large expanses of land still under water, officials say the natural disaster will have a major impact on farm production.

Galwan said the rains and landslides devastated crops in his area, regarded as the country's "salad bowl" for its vegetable farms and strawberry fields.

Rains have subsided in most areas and water was receding Saturday from low-lying provinces south of the Cordillera region, but much of the rice-growing province of Pangasinan, northwest of Manila, was still submerged. In the provincial capital of Dagupan, flood water was about waist-deep.