The vice-chancellor of the Chinese University of Hong Kong, Joseph Sung Jao-yiu, provoked anger among students after he delivered a ceremonial speech in Mandarin first, followed by Cantonese and English.
Cantonese is the de facto official language of Hong Kong, and the major teaching language of the university. Some interpreted his decision to speak in Mandarin first as a sympathetic gesture towards Beijing.
A student senator and student unions of seven of the nine university colleges issued a joint statement condemning the vice-chancellor, the Hong Kong Free Press reported.
According to the statement, he had "abandoned [the] Hong Kong people’s mother tongue". It referred to his decision as "shameful" and accused him of using the ceremony as an opportunity to please China.
During the ceremony, graduates held up signs rejecting a recent interpretation of Hong Kong’s constitutional Basic Law by Beijing in relation to the disqualification of two elected Hong Kong lawmakers critical of China.
Mr Sung responded by saying that he tends to speak whichever language is easiest first, and that such a demonstration at the graduation ceremony was "inappropriate".
At the same ceremony in 2014, students held up yellow umbrellas as a symbol of their solidarity with the pro-democracy Umbrella Movement.