A week of heavy rains caused rivers to overflow, drowning at least 80% of the oil-rich state of Tabasco. Much of the state capital, Villahermosa, looked like New Orleans after Hurricane Katrina, with murky water reaching to second-storey rooftops and desperate people waiting to be rescued.

At least one death was reported and nearly all services, including drinking water and public transport, were shut down as more than 900,000 people in the state of two million had their homes flooded, damaged or cut off.

A 10" natural gas pipeline sprang a leak after flooding apparently washed away soil underneath it, but it was unclear if other facilities operated by the state-run Petroleos Mexicanos were damaged.

Rain gave way to sunshine this weekend but forecasters predicted more precipitation in the coming days. The flooding was not related to a tropical storm which pounded the Caribbean this week.

Tabasco state floods every year around this time. But the quickly rising waters surprised even flood-weary residents, forcing soldiers to evacuate the historic city centre, and the dykes failed last night, flooding the city's bus station and open-air market.

Tens of thousands of people were still stranded on rooftops or inside the upper floors of their homes yesterday.

Rescue workers used tractors, helicopters, jet skis and boats to ferry people to safety, while others swam through poisonous-snake infested waters to reach higher ground.

Calderon met state officials and flew over the affected areas. He ordered the armed forces and federal police to maintain order and prevent looting, and asked residents to try to remain calm. He also cancelled a Latin American trip scheduled for next week.