|The president has urged the country to rally behind the recovery effort [AFP]|
Hundreds of thousands of people have fled the flooded Mexican state of Tabasco amid reports of looting and warnings of a possible outbreak of disease.
A week of heavy rains have caused rivers to overflow, submerging at least 80 per cent of the oil-rich state.
The roads not flooded on Saturday were filled with long lines of cars as residents tried to leave Villahermosa, the state capital, for less affected areas.
Half of the city's petrol stations were out of service, but the exodus appeared to be orderly with no reports of violence
Mauricio Hernandez, a Villahermosa resident, said: "We are leaving because we cannot live like this.
"We don't have any water, and the shelters are full. Where are we going to go?"
At least 6,000 people have fled to shelters in Coatzacoalcos and nearby Minatitlan, both in neighbouring Veracruz state.
Fidel Herrera, the governor of Veracruz, is reported to have sent state buses to Villahermosa to collect flood victims.
Much of Villahermosa has water reaching up to second-story rooftops and people waiting to be rescued.
|There are fears of a cholera outbreak [AFP]|
Tens of thousands of people are still stranded on rooftops or inside the upper floors of their homes.
Rescue workers used tractors, helicopters, jet skis and boats to ferry people to safety, while others swam through snake-infested waters to reach higher ground.
At least one death was reported and nearly all services, including drinking water and public transportation, were shut down as nearly a million people had their homes flooded, damaged or cut off.
Of the estimated 900,000 people left homeless, about 300,000 have yet to be rescued.
Food is scarce, and Mauricio Hernandez, the federal deputy health secretary, warned of possible outbreaks of cholera and other waterborne diseases.
He said: "With so many people packed together there is a chance that infectious diseases could spread."
About 150 of the state's hospitals and clinics were out of commission due to the flooding.
Meanwhile, Felipe Calderon, the Mexican president, ordered the armed forces and federal police to maintain order and prevent looting, but local radio reported that residents had begun raiding local markets for supplies.
Mexico has rallied around the disaster, with people across the country contributing money and supplies.
Calderon called on Mexicans to contribute bottled water, canned goods, nappies and other vital supplies to donation centres around the country.
"Nobody can stand around with his arms crossed," he said.
"We can't and won't abandon our brothers and sisters in Tabasco."