RIVERSIDE, Calif. -

Riverside city and county residents are being warned to be wary of a phone scam during which a caller claiming to be with law enforcement seeks money to clear a up a contempt of court-related arrest warrant.

The scam artist poses as a police officer or sheriff's deputy, sometimes with the rank of lieutenant, and demands that the victim make a payment using a prepaid Green Dot debit card, according to Riverside police Officer Javier Cabrera.

He said the imposter has told victims that they have arrest warrants pending for failure to report for jury duty.

``The caller also attempts to obtain personal information over the telephone,'' Cabrera said.

Green Dot debit cards can be purchased at retail outlets, such as CVS and Kmart, where buyers can load funds onto the cards using cash or by transferring money from their bank or credit card company. Funds can also be added online via PayPal, according to the Green Dot website.

``It is not common practice for the Riverside County Sheriff's Department or the Riverside Police Department to call citizens to notify them of any outstanding warrants,'' Cabrera said. ``Any similar calls are fraudulent and have no connection to the police department, the sheriff's department or the Superior Court.''

Last month, the Corona Police Department's fraud unit warned residents to be alert to a Green Dot scam in which callers were representing themselves as bank loan officers, municipal water and electricity customer service representatives and Internal Revenue Service collection agents, attempting to cajole and frighten people into giving them money to retire past-due debts.

The callers insisted that victims use Green Dot MoneyPak cards to make immediate payments, according to Corona police Sgt. Kim Velasco.

She said scam artists told victims to disclose the serial number on their MoneyPak cards, enabling the crooks to transfer funds from the card.

Anyone who has encountered such a call was urged to report it to their local law enforcement agency.