Bobby Kim, a popular R&B singer in South Korea, was questioned by the U.S. Federal Bureau of Investigation (FBI) after his alleged sexual harassment of a cabin crew member in a flight from Incheon to San Francisco, Korean Air Lines Co. said Friday.

The 42-year-old is accused of inappropriately touching a female crew member as well as hurling sexual insults while intoxicated on the U.S.-bound Jan. 7 flight, according to the South Korean carrier.

The singer was later taken in for questioning by FBI and customs officials upon landing at San Francisco International Airport, along with the flight attendants and two other passengers present at the scene, Korean Air said.

The country to which a carrier is registered has jurisdiction over incidents that take place during flights, but Kim, a U.S. citizen, can also be punished under U.S. law.

"Kim had been upset when he was drinking wine (served during the flight)," the singer's management agency said, explaining that Korean Air had mistakenly seated him in economy class even though he had earlier requested a mileage upgrade to business.

"He says he doesn't remember exactly what he did on that flight," the agency added.

Police here, meanwhile, said they will begin an investigation as soon as Kim returns to South Korea. (Yonhap)