MONTERREY: Torrential rain pounded northern Mexico on Wednesday, triggering floods that closed a US-Mexico border bridge and forced tens of thousands of people to evacuate their homes.

The heaviest rain for several decades has topped off reservoirs in the border states of Coahuila, Nuevo Leon and Tamaulipas, across from Texas, with officials diverting water into swollen rivers to avert major damage.

After Hurricane Alex soaked the region last week with floods that killed at least 15 people in Nuevo Leon, a new storm dumped still more rain on waterlogged terrain.

Some 40,000 homes have already been damaged in Coahuila, said state communications coordinator David Aguillon.

The "Gateway to the Americas" international bridge, one of the busiest border crossings between Texas and Tamaulipas, was closed on Wednesday after the Rio Grande river rose more than 10 meters (yards).

Two other international bridges remained open but under surveillance.

Some 3,500 people were evacuated from their homes in Tamaulipas as several reservoirs spilled over, threatening rural communities with floods.

Authorities have now evacuated some 22,000 people from the town of Anahuac, in Nuevo Leon, for fear that a nearby dam will overflow.

In the town of Linares, Nuevo Leon, the town hall collapsed, in dramatic footage shown on television, as its foundations weakened under the persistent rain, said Mayor Francisco Medina.

More than 100,000 people remained without drinking water around the state following last week`s storms, which caused flooding and chaos in the capital Monterrey, said Javier Trevino, a state government official.

Alex also left a trail of overturned cars and mud-covered roads in its wake and caused an estimated 800 million dollars in property damage, said Nuevo Leon state Governor Rodrigo Medina.

The US National Weather Service has forecast heavy rains over southern Texas and northeast Mexico in the coming days.

BDST: 0823 HRS, July 8, 2010