There have also been reports of bats attacking people.

The outbreak is very grave. The authorities did not take precautionary measures

Yolanda Herrera, veterinarian

Yolanda Herrera, a veterinarian with the Mexico-US Commission for the prevention of foot-and-mouth disease, said about 90% of the cattle deaths were due to rabies transmitted via the vampire bats.

Vampire bats feed on the blood of of mammals and birds. They usually bite cattle, and occasionally humans. Their bite wounds are not serious but may carry diseases such as rabies.

Disease spreading

Ms Herrara said the disease has spread through Chiapas since 1987 as the bats have migrated.

"The outbreak is very grave," she said. "[The authorities] did not take precautionary measures, and there is a delay in the distribution of vaccines by health authorities," she said.

She said the bats need to be eradicated in the areas where they live, such as caves.

Government officials, however, said the rabies outbreak was under control.

Bats have caused rabies in up to 3,000 cattle in Mexico

The chief of health for the state Ministry of Agriculture, David Lopez, said the ministry had provided 60,000 rabies vaccines to local ranchers at a cost of about one peso each, much cheaper than the eight pesos charged by private clinics.

But ranchers said the government was not doing enough to help them

"It's shocking," said cowboy Manuel Perez. "We have never faced a situation so grave," he said.