The unusual attack damaged the zookeeper's stomach, liver and lungs, said Jose Potito, director of the hospital where the woman was being treated.

"The woman's condition is very serious," Potito told local TV channel America.

Anteaters, which can measure up to 9.2 feet (2.8 meters) long and weigh as much as 110 pounds (50 kg), are native to Latin America and have toothless snouts.

They are usually not aggressive, but their long, knife-like claws can do serious damage to predators when they defend themselves.

A worker at the zoo described the attack as an accident and said the animal was not punished in response.