After a tour of southern cities wrecked by flooding, Mexican President Ernesto Zedillo on Saturday declared the natural disaster the second-worst in the country's history.

Zedillo said the destruction caused by the flooding posed a rebuilding challenge second only to the damage from the 1985 Mexico City earthquake, which killed 10,000 people.The flooding has left 400,000 people cut off from the rest of the country and forced 20,000 people from their homes.

Zedillo gathered with 10 Cabinet members in the city of Tapachula, near the Guatemalan border, to lay out the government's plans for cleanup and reconstruction.

"We are mounting an operation that has no precedent in our history," including a temporary jobs program that will begin putting 40,000 people to work Monday, the president said.

The flooding was sparked by a week of steady rain that swelled rivers along the Pacific coast of southern Chiapas state. A 100-mile stretch of coastline has been entirely cut off by dozens of breaks in the coastal highway and a parallel railway line.

Although his government has said that more than 100 people died, Zedillo said that the first systematic count showed that 78 bodies had been recovered. He said he expected the death toll to rise.

Zedillo made the statements after a helicopter tour of the damaged areas. He was surrounded by weeping women in the mountain town of Motozintla, 35 miles north of Tapachula, where a local official said 12 people died and 18 were missing.

"Don't lose hope," the president told relatives of the victims. "After many days of national disaster, the first signs of help are getting through."

Before breaking into tears, Flavio Vasquez told Zedillo that "my two children and wife are buried. Our house collapsed. They have not found them."

Miguel Valdez Galan, the state government's emergency response director, said helicopters were fanning out across the coast, with their first priority to rescue people still clinging to perilous plots of ground near swollen rivers.

"We know what the damages are, and we have them prioritized," Valdez Galan said.

The airborne aid effort was bringing food, water and medicine to the area.

While as many as 1.2 million people were affected by the flooding, only about 25,000 have gone to government-sponsored shelters so far, Zedillo said.

In Puerto Madero, a port town just south of Tapachula, Reina Cecilia Fernandez, 19, woke up Saturday with her husband and 1-year-old baby after spending the night on a warped wooden table on a neighbor's porch.

She fled her own home nearby after river water rose chest-high. "We ran out with what we were wearing and when we came back to check, everything was gone," she said.

Fernandez said her family had no water to drink except for the floodwater that surrounds and fills her house, and they couldn't afford enough cooking gas to boil the water.

"Yesterday we went to the relief center to get water, but they wouldn't give us any," she said, wading through the street as she breast-fed her baby. "So, we're drinking the water that's here, even though it's dirty."