Aggressive scammers are busy this holiday season posing as IRS agents and have already phoned hundreds of Hawaii residents trying to bilk them out of cash.

The latest wave of phone-call scamming has intensified in the last three weeks or so, with the would-be thieves making persistent demands with repetitive calls. In many cases the scammers make it appear that the calls come from the Honolulu Police Department’s general phone number or from mainland cities.

“We’re not making the call,” Honolulu police Capt. John McCarthy said. “It’s not the way business is done. The IRS doesn’t call and threaten to sue.”

The perpetrators are likely calling from outside the United States but are able to spoof U.S. telephone numbers, often using Voice over Internet Protocol (VoIP) numbers, which are difficult to trace and cannot be blocked, he said. But in some cases, in which the scammer offers to meet the victim to pick up money, the scammer may be a local resident.

Police are warning the public not to fall prey by providing personal or financial information or by sending money to the thieves.

McCarthy said some Hawaii residents have fallen for the scams and have paid out money, but he did not have any estimates. “It’s the Christmas season, and people have other concerns, so people will give,” he said.

Many of the callers make the bogus claim that they’re IRS officials and assert that unless the recipient of the call pays up on alleged back taxes, the IRS will sue.

But McCarthy said IRS agents don’t collect money and would never call to ask for disclosure of personal information pertaining to finances and accounts. He encourages anyone thinking such a call may be legitimate to call the agency to verify the origin of the request.

McCarthy said the latest scam appears to be a variation on older scams, such as callers claiming to be representing a sheriff’s office or the FBI, both contending, “You owe me money.”

The IRS scammers appear to be calling residents statewide. “I got a phone call myself last night,” McCarthy said.

He urges people who get such calls to simply hang up.

“Don’t engage with them,” he said. Scammers are skillful at eliciting information, and some have been vindictive with their victims, McCarthy warned.

“It’s next to impossible” to catch the thieves, he said, but asks people to report such bogus calls to police. “It tells us it’s a problem we have to address.”