The Siberian Tiger Park in Harbin, Northeast China's Heilongjiang province, is helping more than 300 Siberian tigers to lose weight by adding more exercise to their daily routine and cutting back on their food intake.

Photos of the tigers circulated online and received wide attention from netizens, who compared the endangered big cats to orange tabby cats such as comic-strip character Garfield.

Netizens questioned whether the captive tigers have been overfed by tourists at the park, the world's largest Siberian tiger breeding and field training center.

Liu Dan, chief engineer at the park, said the tigers' obesity is a seasonal phenomena.

"Some of tigers in the park look very chubby, but it has nothing to do with tourists feeding them. In fact, it is natural for these animals to devour more in order to adapt to acute weather conditions during the winter," he said.

The weight of a male Siberian tiger, normally about 250 kilograms, increases by about 10 percent in winter, Liu said, adding that food intake for the big cats increases by about 30 percent to 6 to 8 kg daily.

"When feeding them, we drop the food on the ground and let them fight for it. So some tigers get more food than others," Liu said. "The chubby tigers in the photos are less than 2 years old, so their rolls of fat are just like a child with baby fat."

Liu added that with spring approaching, the park is cutting food supply to make sure the tigers are healthy during the mating season.

"In addition, we guide them to do more exercise when dropping their food," he said.

On Feb 23, tigers at the park were recorded chasing an exercise drone, with one tiger leaping into the air and striking the drone.

Siberian tigers were once found throughout the Russian Far East, northern China and the Korean Peninsula. By the 1940s, hunting had driven the tiger to the brink of extinction - with no more than 40 individuals remaining in the wild.

According to WWF, there are about 540 wild tigers around the world. From 2012 to 2014, at least 27 wild Siberian tigers were spotted in Northeast China.