Chinese state media recorded the cause of his passing as "an infection with a severe cold".

Faculty members learned of his death in a post on Chinese social media platform Wechat at Tsinghua University's Academy of Arts and Design, where Wu had been a professor.

Staff at the University would only confirm that he had "died of an illness" and would not say if COVID-19 had been the cause of death.

Some 14 death notices have been issued on the University website this month, but none have specified whether COVID-19 was the cause, prompting widespread discussions on social media platforms.

COVID-19 related deaths remain a matter of dispute in China since restrictions were lifted earlier in the month after a strict lockdown.

China's National Health Commission reported 3,761 new cases in the previous 24 hours on Friday.

The Wall Street Journal has claimed there has been an increase in activity at Beijing’s Dongjiao Crematorium, a facility designated by the National Health Commission to deal with COVID-19 cremations.

Dr Wang Guangfa, respiratory and critical care medicine director at Peking University First Hospital has warned that a spike in cases over the next few weeks should be expected in an article which appeared in the state run Global Times.

During the Beijing 2022 Winter Olympics earlier this year, a "closed loop" system restricted Games participants, officials and media to designated areas and the Asian Games in Hangzhou, originally scheduled for September 2022, were postponed until next year as a precautionary measure.

Other international sporting events have also been moved from China because of the virus.

In Wu's last social media post made on Weibo on December 9, he had warned: "We should all be careful."

Wu had posted a photograph of a painting of a rabbit on the door of his house asking visitors to "please leave express deliveries at the door and small items in the cardboard box, thank you."

His design of a rabbit had been chosen for the stamp to commemorate Chinese New Year in 2023.

Wu who came from Zhongshan, in Southern China’s Guangdong province, had been a renowned artist and designer who led the team which produced the five mascots for the Beijing 2008 Olympics.

The mascots known as  Fuwa or "Friendlies" were called Beibei, Jingjing, Huanhuan, Yingying, Nini and were inspired by the "playful qualities of five little children".

When the names were linked together, they formed the sentence "Welcome to Beijing".

Wu was also responsible for Fu Niu Lele, the mascot for the 2008 Summer Paralympics in Beijing.

Beijing 2008 gave him a special honorary award for his work with the Olympic and Paralympic mascots.

Wu retired from Tsinghua University in November 2021.