SEOUL (REUTERS/KOREA HERALD/ASIA NEWS NETWORK) - The chairman of Korean Air apologised on Friday for an incident involving his daughter who delayed a flight last week because she was unhappy about the way she was served nuts while seated in first class.

Cho Yang Ho said he would have Heather Cho removed from all posts at the company's affiliates following her resignation as vice-president at the South Korean flag carrier where she was responsible for in-flight service.

"Regardless of the (ongoing) probe by the transport ministry and prosecutors, I will have Heather Cho step down from not only vice-president at Korean Air but all posts at affiliates," Cho said at a news conference at the company's headquarters.

The 65-year-old businessman asked for the public's forgiveness for the "foolish" actions of his daughter, reported Korea Herald Friday.

"I am making my apology as a father and head of Korean Air," he said at the airline's headquarters in Seoul.

Before the uproar, dubbed "nut rage" in South Korea, Cho Hyun Ah, also known by her English name Heather, was vice-president of the airline's flight service and hotel operations. She was chief executive of KAL Hotel Network, Wangsan Leisure Development Co. and Hanjin Travel Service Co., all affiliates of Hanjin Group. She is currently a director of the board of Korean Air. Hanjin is the parent company of Korean Air and is one of the top 10 family-run business conglomerates in South Korea. It is founded in 1945 by Mr Cho Choong Hoon, the incumbent chairman's father.

The repercussions of the incident are expected to build as Ms Cho faces a government summons to question her on why she caused the delay, the Transport Ministry said on Thursday.

The ministry issued a notification requesting her appearance for questioning on Friday, said Mr Lee Gwang Hee, aviation safety division director of the Ministry of Land, Infrastructure and Transport.

Ms Cho will appear for the questioning, the company said.

The ministry has also asked Korean Air to supply the list of passengers on the Friday flight, with their contact information, to clarify the facts. Korean Air has yet to comply.

The authorities are urging passengers to come forward and talk about what really happened. They have finished questioning 10 Korean Air employees, including the pilot of flight KE086 and the cabin crew.

Adding more pressure to Korean Air, the Seoul Seobu District Prosecutors' Office on Thursday raided the airline's Seoul and Incheon headquarters to collect documents including the black box and flight operation records of the plane in question.

"We conducted a hasty raid as the case has drawn public attention and concerns over fabrication of evidence," a prosecution official said.

After analysing the documents, the prosecutors plan to question Ms Cho, who is suspected of violating aviation safety law and obstruction of business.

A day before, progressive civic group the People's Solidarity for Participatory Democracy had filed a complaint with the prosecution, claiming that Korean Air's management has forced its employees to make false testimonies to put the blame on the chief flight attendant who was forced to leave the plane.

The authorities are currently investigating whether Ms Cho's actions infringed aviation laws.

The key points of the investigation include whether she was shouting while on board and detailed reasons for why the employee left the plane, and why the plane had to return to the terminal.

On Tuesday, Ms Cho stepped down from all posts at Korean Air except as executive vice-president. The day after, she said she would resign from this position as well.

Korean Air's labour union has demanded a formal apology from Ms Cho to the employees for violating their rights.