Korean Air Lines has said it will allow crew members to “readily use stun guns” to manage in-flight disturbances, after being criticised by US singer Richard Marx for its handling of an incident involving a violent passenger.

The South Korean carrier also said on Tuesday it will beef up security training of crew members.

Last week, Marx said on Facebook and Twitter he helped initially subdue “a psycho passenger attacking crew members and other passengers”. He also accused crew members of being “ill-trained” and “ill-equipped” to handle the “chaotic and dangerous event”.

Marx’s wife, Daisy Fuentes, who was with the singer during the flight from Vietnam to South Korea, said on Instagram that crew members “didn’t know how to use the taser & they didn’t know how to secure the rope around him (he got loose from their rope restraints 3 times)”.

Korean Air Lines said on Tuesday its crew members were “hesitant” to use taser guns because they were permitted for use on only “grave” situations which jeopardise the life of a passenger or crew member or the safety of a flight.

“We have decided to improve our conditions and procedure on using Taser guns to cope with violent acts and disturbances on board in a fast and efficient manner,” it said in a statement, without elaborating on how it would revise the rules.

However, a spokesman said the changes would ease conditions on using Taser guns so that crew can “readily use stun guns”.

In South Korea, the number of unlawful acts committed aboard planes has more than tripled in the past five years, according to government data.

Video footage of the recent incident posted on YouTube showed a young man in a business class seat spitting and swearing at crew members trying to restrain him with a rope.

On Monday, the passenger appeared for questioning by police, wearing a mask, thick-rimmed glasses and a hat. He apologised for his behaviour but said he could not remember what had happened, according to video shown by broadcaster SBS.