Lin Yuwei and Wu Yanni, China’s entrants in the women’s 100m hurdles final, embraced after the race at the Asian Games in Hangzhou. Lin won gold in the race with a time of 12.74 seconds. A photograph of the two women in profile showed Lin’s lane number, 6, next to Wu’s lane number, 4.

“6/4” is a common reference to the Tiananmen Square massacre in the early hours of 4 June 1989. Discussion of the killings and the protests that preceded them are strictly controlled in China, with a wide range of references routinely scrubbed from China’s internet.

Posts on Chinese social media app Weibo that mention the two athletes hugging showed grey squares where the photograph should have been.