Cathay Pacific Airways Ltd. apologized again on Tuesday and suspended its cabin crew staff after a Mandarin-speaking customer accused them of discriminating against passengers who don’t speak English.

The airline has launched an internal investigation after it became aware of an “unpleasant experience” by a passenger onboard the CX987 flight between Chengdu and Hong Kong, it said on its Weibo account, without going into details of the incident.

Cathay said it has contacted the passenger in question and has suspended an unspecified number of flight attendants involved in the incident. Outcome of its internal probe will be announced in three days, it added.