Giant panda Le Le, who died early this month in the Memphis Zoo in the United States, may have succumbed to heart disease, a joint autopsy by Chinese and US experts has showed.

Based on the cardiac lesion they observed, the experts have preliminarily judged that this was what caused the death of the panda born in 1998, according to a media release from the Chinese Association of Zoological Gardens on Sunday.

"But further pathological diagnose is still needed to confirm the cause," it said.

The autopsy was conducted after a Chinese expert group arrived at the Memphis Zoo recently. Experts of the two countries ruled out some common diseases that may have caused Le Le's death, such as intestinal twist, aortoclasia and ruptured pyogenic liver abscess.

Le Le died just when he was to be sent back to China very soon.

The male panda died in his sleep on Feb 3, Xinhua News Agency quoted an unnamed spokesperson from the Memphis Zoo in a report in early February.

Le Le came to the zoo with a female giant panda, Ya Ya, in 2003.

In December, the zoo said that the iconic duo would "make the journey back to China within the next few months" as the current giant panda loan agreement with the Chinese Association of Zoological Gardens was coming to an end.