BEIJING • An airline based in south-west China has vowed to hold accountable those behind a scandal in which security staff allegedly compelled new flight attendants to cram into overhead compartments as "a rite of passage", according to media reports yesterday.

Kunming Airlines, headquartered in Yunnan province, scrambled to deny that it had acquiesced to this practice, which Chinese media said started four years ago. It said it had no knowledge of the practice until a social media user shed light on it in a post on Sunday night.

The post by "caccsky" on WeChat, a popular instant messaging system in China, disclosed that nearly all new flight attendants of Kunming Airlines, after completing 30 to 50 hours service, have to go through the ritual to be recognised as part of the team.

"No newbie has been exempted, except for a few who are taciturn. But they were often stigmatised as 'uncooperative' and 'cocky'," said the post, featuring several photos of flight attendants being tucked into overhead compartments.

The post added that many flight attendants were upset by the practice, but they did not air their grievances for fear of being isolated.

The post went viral within hours and hit the headlines, prompting the airline to pledge an investigation and punish those responsible.

"Such conduct is the personal behaviour of certain cabin crew and security staff, which the airline has no knowledge of and never encourages," its statement said, adding that the company did not find the practice a threat to passengers' safety as it took place only after flights.