Loaned out as part of China's "panda diplomacy" programme, the distinctive black-and-white animals have symbolised friendship between Beijing and Tokyo since the normalisation of diplomatic ties in 1972.

Japan currently has only two pandas, Lei Lei and Xiao Xiao, at Tokyo's Zoological Gardens in the Ueno neighbourhood.

But the twins are now set to be repatriated a month before their loan period expires in February, said Tokyo Metropolitan Government, which operates the Ueno zoo.

Tokyo's regional government has been asking for the immensely popular mammals to remain at the zoo -- where they attract huge crowds -- but China didn't agree, according to the Nikkei business daily.

In September last year, animal lovers in Tokyo bid farewell to the parents of Lei Lei and Xiao Xiao who returned home.

Just before they left, thousands of tearful fans came out to catch a final glimpse and take photographs of the beloved bears.

The Asahi Shimbun reported that Tokyo is seeking the loan of a new pair, although their arrival before the return of Lei Lei and Xiao Xiao is seen as unlikely.

Ties between Asia's two largest economies are fast deteriorating after Japan's conservative premier Sanae Takaichi hinted that Tokyo could intervene militarily in the event of any attack on Taiwan.

Her comment provoked the ire of Beijing, which regards the island as its own territory.

Japan's top government spokesman Minoru Kihara said pandas have helped ties with China.

"Exchanges through pandas have contributed to improving the feelings between the people of Japan and China. We hope such exchanges will continue," Kihara told a regular press briefing.

He said that "several local governments and zoos have expressed interest in receiving pandas on loan", but did not state whether the national government was asking China for new animals.

The Ueno zoo has long been the beneficiary of panda diplomacy, having cooperated with facilities in China and the United States to successfully breed giant pandas.

Lei Lei and Xiao Xiao were delivered in 2021 by their mother Shin Shin, who arrived in 2011 and was returned to China last year.

Breeding pandas in a zoo environment is fiendishly tricky due to their difficulties mating, false pregnancies and high mortality rates of newborn cubs.