Members of a K-pop girl band detained at the Los Angeles airport and sent back to South Korea lacked the proper work visas, the Los Angeles Times reported Sunday.

The agency that represents the band Oh My Girl, WM Entertainment, said that US immigration authorities suspected that they might be sex workers after the eight performers were held at the Los Angeles airport for 15 hours on December 9.

Not true, an official with the US Customs and Border Patrol told the Times.

Band members were seeking to enter under a program that allows South Koreans to travel in the United States for up to 90 days without a visa, the official said.

But when customs agents went through their luggage and found costumes and props it was clear that they had arrived to perform.

The US agents denied the young women entry because they lacked the required P1 performance visa.

"We were doing what we do every day," the official, who spoke on condition of anonymity, told the Times. "We send people back all the time."

WM Entertainment said in a statement in South Korea that US immigration authorities "seem to have mistaken them as sex workers" after going through their luggage, "probably because of their young age."

The band was booked to perform at a gala event in Los Angeles on Saturday, the statement read.

The statement also hinted that there might have been an issue with the type of visa the band members were holding.

Oh My Girl was formed in March and released its debut single in April.

South Korea's K-pop scene, which has been exported with enormous success, is dominated by girl and boy bands whose members are sometimes as young as 13 or 14 years old.