(This version of the story corrects to add reference to a cup in paragraph three)
By Christine Kim and Joori Roh
SEOUL (Reuters) - South Korean police have launched an inquiry into reports a daughter of the chairman of Korean Air Lines threw a water bottle at someone's face, the second daughter of the airline chief to get into trouble over an angry outburst.
Cho Hyun-min, a senior vice president at the airline, apologised on Thursday for her "foolish behaviour", following media reports that she threw a water bottle at the face of a manager at the airline's advertising agency.
In her apology on her Facebook page, Cho did not give details of the incident and an airline spokesman said she had thrown a water bottle or a cup on the floor, not at anyone's face.
Cho's older sister, Heather Cho, made headlines over a notorious "nut rage" incident in 2014, when she lost her temper over the way she was served nuts in first class and ordered the Korean Air Lines plane she was on to return to its gate at a New York airport.
Police had launched a preliminary investigation to see whether Cho Hyun-min had abused her power or broken any law in connection with the latest reports, an official at Seoul Gangseo Police Station told Reuters on Friday.
The official gave no details of the inquiry. Such inquiries are carried out to determine if a formal investigation of an incident is warranted.
A Korean Air Lines spokesman said the company had yet to be informed of any preliminary investigation.
The airline's chairman, Cho Yang-ho, has not commented on the incident involving his younger daughter, who has left the country on a vacation, the company said.
The behaviour of the rich and powerful is sensitive in a country where the economy is dominated by family-run conglomerates know as chaebol, particularly days after a court jailed former President Park Geun-hye for 24 years over a scandal that exposed deep ties of corruption with several chaebol.
Korean Air Lines was not connected to the Park scandal.
Thousands of people have in recent days posted comments on a presidential office website where members of the public can lodge petitions, to demand changes at the airline.
Many of the people who signed a few dozen petitions demanded that the airline remove the word "Korean" from its name and stop using the symbol on the Korean flag as its logo.
Many said the daughters' behaviour was "degrading" for the country and the company.
A petition needs to gain more than 200,000 signatures within 30 days to prompt a mandatory response from the presidential office.
Heather Cho was found guilty of breaking aviation law and jailed for a year over her "nut rage" incident but was freed in May 2015 after an appeal.
(Reporting by Christine Kim and Joori Roh; Editing by Robert Birsel)