The state attorney general's office is warning Pennsylvanians about an international long-distance phone scam that is duping consumers into ringing up massive phone bills and could lead to identity theft.

The perpetrators leave phone and text messages asking people to call to confirm a lottery or sweepstakes prize. Another ploy asks people to call for information on a relative who has been injured or hospitalized.

People who return the messages actually are calling unregulated international long-distance phone numbers, mainly in the Caribbean, and can be charged hundreds of dollars per minute for the calls, the attorney general's office said. In most cases, the thieves are trying to get consumers to divulge personal or financial information, but even callers who don't bite on that part of the scam can be hit with massive phone bills, the office said.

The scam isn't new, but the attorney general's office decided to issue an alert because of the large number of complaints it has received in the last few weeks, spokesman Nils Frederiksen said. Although the complaints have been centered in southeastern Pennsylvania, the ruse is believed to be happening statewide.

"Because there is a delay between when people make the call and notice it on their phone bills, we wanted to cut this off as soon as possible," Mr. Frederiksen said.

Before returning an unsolicited call, consumers can ask directory assistance or an operator to check the location of an unfamiliar number and ask about the per-minute charges for the number, the attorney general's office said.

Consumers are urged to check their monthly phone bills and dispute any suspicious calls.

"If you made one of these calls unknowingly, dispute it immediately with the phone company. You should not be on the hook for it," Mr. Frederiksen said.