Chinese-American business owners and professionals across the country are being targeted by an anonymous Mandarin-speaking caller seeking money and often threatening them and their families, authorities and business leaders said.

The calls, apparently originating in China from someone with a Taiwanese or Fujianese accent, have targeted people in at least seven states, from California to Massachusetts. Cities where the threats have been made include New York, Boston, Philadelphia and Toronto.

"They were saying, 'We know where you live, we know your family members,"' said Steven Zhu, liaison officer of Chinatown Town Watch in Philadelphia. At least 20 people in the city or its suburbs have been targeted during the past two weeks by someone seeking $10,000 to $30,000, and a Montgomery County resident ended up wiring a large amount, police said.

Several calls have not involved threats but have been appeals based on ethnic origin to get cash, for example, to help someone get out of jail, Lt. Dennis Cullen of the police Criminal Intelligence Unit said.

FBI officials on Friday acknowledged "a nationwide attempt to extort business owners ... through phone calls threatening violence." Officials said the callers, apparently based in China, try to provide enough personal data about the Asian American victims to convince them that they are in danger, but use only information available on the Internet.

"There have been no reported incidents of violence actually perpetrated," Matthew Heron, section chief of the FBI's Organized Crime Section in Washington, said in a statement. An FBI spokesman said such calls had been reported in California, New York, Massachusetts, Illinois, Florida and Texas.

Since mid-March, "scores" of calls have been made to doctors, attorneys and accountants in the San Gabriel Valley area east of downtown Los Angeles by callers demanding $30,000 to $50,000, said Steve Whitmore, spokesman for the L.A. Sheriff's Department.

"He's also leaving phone messages, which ... indicates that he's somewhat brazen," Whitmore said.

About three dozen cases have been reported in Boston and the surrounding cities of Brookline, Cambridge and Quincy, said Gilbert Ho, president of Boston's Chinese Consolidated Benevolent Association and a member of the city's Chinatown Crime Watch.

"If a person answers using English or another language, they will hang up; they only speak Mandarin," he said.

He said authorities have told him the perpetrators appear to be using Internet phones and the money was to be wired to an address in China. The callers also may be using an Internet mapping program to describe the area of a victim's store, Ho said.

"They describe nearby landmarks, so the businessman thinks maybe they are nearby, so they become more scared," he said.

Mike Lu, owner of BJ Wood Flooring, a building supply company in South Philadelphia, said Monday's call demanding $30,000 frightened his wife so badly she did not want to come to work the next day.

"He said he's got a gun, he's got a lot of people, East coast, West coast," Lu said.

Capt. Brian Korn of the 6th police district, which includes Chinatown, said the caller or callers may be targeting names out of Chinatown business directories or some other public source, since they sometimes had inaccurate or outdated information.

"One person ... said 'We have your daughter,' when his daughter was standing right next to him when he was on the phone," Korn said.

One Boston-area business owner was relieved when the caller began describing an old neighborhood from which the store had relocated a year ago, Ho said.

Law enforcement officials in Philadelphia met with several dozen Chinatown merchants this week to urge them not to give the caller any money or personal information, and to try to identify the number if possible and notify police immediately.

Officials in several states cited recent law enforcement efforts to build bridges to the Asian American community as helping to quickly spread the word about the scam.

"Something like this a few years ago might have gone weeks before the police department ever got notified of it," Korn said. "Rumors might have been circulating around Chinatown, (people) calling each other, business leaders or associations but never the police. ... I think it's a success that we were able to get on top of this real quick and get the word out."