(Reuters) - An antelope choked to death at a Tennessee zoo last week after swallowing a plastic cap from a squeezable food pouch that a guest apparently brought into the animal park in violation of its safety rules.

Lief, a 7-year-old male sitatunga antelope, died on Saturday, said Brights Zoo in rural Limestone, about 70 miles (115 kilometers) east of Knoxville, Tennessee.

"Some ask why we don't allow squeezable pouches into the zoo," Brights wrote in a series of social media posts. "The reason is simple - the packaging is dangerous to our animals. Today we lost a beloved animal due to choking."

To mitigate such risks, the private, family-owned zoo requires bags carried by guests to be searched, "yet some people find ways to sneak these in," it said.

Sitatungas, also known as marshbucks, are native to the forests and wetlands of central Africa, where there are an estimated 90,000 to 120,000 mature individuals, according to the International Union for Conservation of Nature.

The conservation organization had designated the species as "Least Concern" in its last assessment of its conservation status in 2016.

In captivity, the species has a life expectancy of 22 years, according to the Smithsonian's National Zoo.

Brights Zoo officials wrote that they believed they would be unable to identify the culprit in Lief's death, which they mourned, writing that he "still had a lot of life to live."

(Reporting by Jonathan Allen in New York; Editing by Bill Berkrot)