Hawaiian Electric is warning customers about a telephone scam involving utility impersonators.

The company says at least a half-dozen small business customers have reported receiving phone calls saying their electric bill is delinquent and that they’re subject to immediate disconnection.

The businesses were directed to pay their bills by purchasing a reloadable prepaid card. The company said Tuesday that prepaid cards are not legitimate payment methods. 

Customers are asked to report suspicious activity to police.