A secondary school in Tsuen Wan confirmed late on Monday that it had suspended 14 pupils for three days, saying that they disrespected the national anthem and emblem by failing to turn up for a flag-raising ceremony.
St Francis Xavier's School said that besides failing to attend the assembly on Wednesday, the pupils had "committed disrespectful acts", without providing further details.
Media reports said some of the pupils were having breakfast in the covered playground when the national anthem began to play.
Speaking on Commercial Radio on Tuesday, education sector lawmaker Chu Kwok-keung said class suspension was a "quite serious" penalty.
While he refused to comment directly on the incident, he said that schools should weigh how a punishment can help pupils recognise their mistakes.
"The best way is to use the appropriate penalties to teach them within the school, as class suspensions may affect their learning and they may not be able to catch up on progress," Chu said.
The Education Bureau said it was seeking a report on the incident from the school. It said there are clear rules governing etiquette during the national anthem and flag-raising ceremony.