Korean Air said it will allow crew members to "readily use stun guns" to manage in-flight disturbances, after coming in for criticism from U.S. 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.

In South Korea, the number of unlawful acts committed aboard airplanes has more than tripled over 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 spat and swore at crew members trying to restrain him with a rope.

"Stop it, you sons of a bitch!" the passenger said in Korean, spitting at airline staff as they used cable ties and a rope to restrain him. "Do what you like!"

On Monday, the passenger appeared for questioning by police, wearing a mask, thick-rimmed glasses and a hat.

He apologized for his behavior but said he could not remember what had happened, according to video shown by broadcaster SBS.

(Source: Reuters)