Korean Air heiress Heather Cho behaved "like a beast that found its prey" during the so-called "nut rage" incident on a flight, a chief steward has told a court.

Park Chang-jin also said Cho, who quit as vice president responsible for cabin service at the family-run airline in the face of a public backlash, treated flight crew like "feudal slaves".

Cho, the eldest daughter of the airline's chief Cho Yang-Ho, is charged with breaking aviation laws and conspiring with other company executives to force crew members lie about the incident in December.

She faces 10 years in jail if convicted of breaking aviation law.

Cho demanded Mr Park be removed from a flight at New York's John F Kennedy airport after a first-class flight attendant served her macadamia nuts in a packet rather than a bowl.

The plane, already taxiing towards the runway, was forced to return to the gate.

Mr Park told the court in the South Korean capital Seoul that Cho "was like a beast that found its prey gritting its teeth as she became abusive, not listening to what I had to say at all".

He also said Cho made him kneel and beg for forgiveness as she jabbed him with a service manual, the court heard.

Fighting back tears, he added: "I don't think Cho showed an ounce of conscience, treating powerless people like myself like feudal slaves, forcing us to sacrifice and treating it as if it was the natural thing to do."

He appeared in court in uniform after returning to work over the weekend following a leave of absence.

Cho's father apologised in court on Friday to Mr Park and promised he would not face any sanction.

Her lawyers previously told the court that she was sorry for her actions, but that they did not merit punishment. They also denied that she used violence.

Prosecutors claim Mr Park was forced to kneel and that Cho jabbed him with a service manual.

Cho, also known as Cho Hyun-ah, has been in custody since 30 December.

Her two siblings are executives at the airline, which is South Korea's biggest.