A team of Chinese experts arrived in Japan today to investigate the death of a giant panda which was on loan to a Japanese zoo, a report said.
Kou Kou died last week of cardiac arrest after failing to recover from an anaesthetic at the Oji Zoo in the western port city of Kobe.
Veterinarians had sedated the 14-year-old male as part of a programme to impregnate his partner Tan Tan, and were seeking to extract semen from the male panda when he died.
The panda's death comes at a time when relations between the two countries are at their lowest point in years, stemming from a collision last week between a Chinese fishing trawler and two Japanese coastguard vessels near a disputed island chain.
The three Chinese panda experts, including one from the China Wildlife Conservation Association, will work with the Japanese side to determine the cause of death, Jiji Press news agency said.
A breeding agreement between Beijing and Tokyo includes the stipulation that Japan pay USD 500,000 in compensation if a panda dies due to human error.
Chinese experts believe Kou Kou could have died from an overdose of sedatives and were questioning why Japanese veterinarians were extracting semen outside the animal's mating period, Chinese state press reported on Monday.
Giant pandas, a highly endangered species native to parts of China, are notoriously slow at reproducing in captivity.
The death of Kou Kou comes after Tokyo's Ueno Zoo reached an agreement in July to receive a pair of pandas from China in a deal that will cost nearly one million dollars a year for the next decade.
The money is to be spent on protecting wild animals in China.
There are just 1,600 pandas left in the wild. Nearly 300 others are in captive-breeding programmes worldwide, mainly in China, according to official reports.