Authorities said nine people were arrested Thursday as investigators broke an international sex-trafficking ring that smuggled Asian women into the U.S. in shipping containers.

Seven conspirators in a "highly organized national network prostitution ring" were arrested in Seattle and two in Los Angeles, the U.S. attorney's office said.

According to court documents, Yong Jun Kang, 36, of Seattle, operated brothels in Portland, Ore., and Seattle, where he and others would bring Asian women, most of whom were in the United States illegally.

Authorities allege that Kang told confidential informants that women were being smuggled into the U.S. in shipping containers after paying as much as $50,000. Some of the women, investigators said, were brought into the United States by crossing the Canadian border.

The women came from China, Korea, Thailand, Vietnam, Malaysia, Singapore, Hong Kong, Japan, Taiwan and Laos, and were forced to pay debts to smugglers by working in brothels, federal prosecutors said.

Others arrested are accused of managing the brothels, transporting prostitutes and operating an escort service that allegedly served as a front for prostitution. A woman identified as a prostitute and a close confidant of Kang's also was arrested.

They face charges of conspiracy to transport individuals in furtherance of prostitution, conspiracy to transport and harbor illegal aliens and conspiracy to engage in money laundering. If convicted, they face up to 20 years in prison.

A message left with Kang's attorney Thursday afternoon was not immediately returned.

Authorities said the 21-month investigation by the FBI, U.S. Immigration and Customs Enforcement and Seattle police used confidential informants, court-approved wiretaps and Global Positioning Satellite units to identify participants.