China said Thursday it had signed agreements to send pandas to a zoo in San Diego, after nearly all the beloved black-and-white animals on loan in the United States were returned during years of diplomatic tensions.

Foreign ministry spokesperson Mao Ning told a regular press briefing that "Chinese institutions have already signed agreements with... the San Diego Zoo in the US".

The agreement centred "on a new round of cooperation in giant panda protection", she said.

A deal was also signed with a zoo in Madrid, and Beijing is in talks with zoos in Washington and Vienna, she added.

China has long deployed the fluffy envoys to various countries as "panda diplomacy", often to further its foreign policy aims.

Tensions between Washington and Beijing mean that only a handful of the bears remain in the United States, with three having left the national zoo in Washington in November.

The last remaining pandas in the United States, currently at a zoo in the southern city of Atlanta, are due to return to China by late 2024.

But after a meeting last year with US President Joe Biden, Chinese leader Xi Jinping said that China could send new pandas as "envoys of friendship between the Chinese and American people."

The White House said it would be happy to have more of the bamboo-chewing bears.

"Giant pandas are a national treasure of China and are deeply loved by people all over the world," Mao said on Thursday.

"We look forward to a new round of international cooperation on the protection of giant pandas with the relevant countries," she said.

There are an estimated 1,860 giant pandas left in the wild, according to environmental group WWF, and about 600 in captivity in panda centres, zoos and wildlife parks worldwide.