Some 300,000 people were still waiting on Friday night to be rescued from the worst floods to hit the Mexican state of Tabasco in 50 years, officials said.

A week of heavy rains, which caused rivers to overflow, has left at least 70 pc of Tabasco and 80 pc of the state capital, Villahermosa, under water.

The homes of an estimated 700,000 people were flooded and potable water supplies in Villahermosa were exhausted, said the governor, Andres Granier. At least one death was reported.

Rescue workers in boats and helicopters plucked desperate residents from their rooftops and led thousands to shelters, but many remained trapped.

“The situation is extraordinarily grave. This is one of the worst natural disasters in the history of the country,” said the president, Felipe Calderon, in a televised address last night.

The Grijalva river, one of two large waterways ringing Villahermosa, has risen two metres above its “critical” level, causing it to gush into the city centre. The state of Chiapas, which borders Tabasco to the south, also reported serious flooding, with an estimated 100,000 people affected, according to officials.

Mr Calderon called on Mexicans to contribute bottled water, canned goods, nappies and other vital supplies to donation centres around the country.