Mexico's president is calling it the tragedy of the decade. At least 330 people have been killed by floods and mudslides in southeastern Mexico. And Ernesto Zedillo says the numbers are rising by the hour.

As the number of dead rises, mayors from several of the affected towns are criticizing the government's slow reaction to the national disaster.

Some called for emergency aid via SOS messages on the Internet as early as Wednesday but the federal government didn't respond.

The Interior Ministry says roads and bridges have washed away, making it difficult to deliver food and medicine to the hundreds of people who need them.

Military personnel say they, too, are finding it difficult to reach some remote mountain villages. Still, President Ernesto Zedillo has ordered a major air and land lift of hundreds of tonnes of supplies.

Hundreds of people are without shelter in many parts of Mexico under the unrelenting rain that has caused a week of severe and deadly floods and mudslides.

Officials have declared a state of emergency in a number of states, with the state of Veracruz on the Gulf believed to have been hardest hit.

The situation represents the worst floods to hit Mexico in 40 years. And there's still more rain in the forecast.

The death toll, which has climbed steadily over the past week, is expected to continue its rise as hundreds of people are still missing.

In Villahermosa, capital of the state of Tabasco, rivers flooded homes with 1.5 metres of water, forcing residents to flee in boats with their belongings. The mayor of Villahermosa, where 500,000 people live, said it was impossible to control the flow of water.

More than 150,000 people have been evacuated from Tabasco, where so far four people have died.

The tragedy is so extensive that national media can barely keep up with the changing statistics of dead and injured.

Newspapers and television stations in Mexico City are urging people to bring food, clothing, blankets and medicine for the victims to collection centres in the capital.