Advance fee scams are targeting non-U.S. investors using fake websites purporting to be U.S. regulators, warns the Washington, D.C.-based U.S. Financial Industry Regulatory Authority (FINRA).

FINRA issued an investor alert on Friday aimed at non-U.S. investors, warning that scammers are using phony regulator websites and fake identities to carry out fraudulent scams.

“No regulator is immune. In fact, in a recent twist, some scammers have misused FINRA’s name and impersonated FINRA employees in email correspondence in an apparent attempt to lend legitimacy to their schemes,” the U.S. regulator reports.

These scams are generally advance fee scams that ask investors to pay upfront fees to facilitate the sale of an investor’s shares that are otherwise worthless. Fake regulator websites are being used to build legitimacy for the scam artist with potential victims, the alert notes.

Investors are also being solicited to recover “non-performing investments” from securities firms that have been fined or disciplined by regulators. “Using official-looking documents, the imposters ultimately seek advance payment for the return of funds lost during the time the investor was associated with the disciplined firm,” it says.

Another scheme involves fraudsters impersonating the U.S. Securities Investor Protection Corp. (SIPC), to trick victims into sending money, or giving the fraudsters access to brokerage accounts and sharing personal information.

FINRA says that it has also seen an instance of fraudulent use of its BrokerCheck system by a scammer who encouraged a victim to check his registration on the BrokerCheck system. “In reality, the caller was an impersonator who stole the name of a legitimate securities professional and boldly used FINRA BrokerCheck for fraudulent purposes,” FINRA says, adding that it knows of more than 50 legitimate U.S. securities firms and individual brokers whose identities have been hijacked by scammers.

Other schemes involve fabricating an official regulator; and using fake letterhead, and, or false addresses and answering machines to trick investors.

“Because it is very difficult for regulators and law enforcement agencies to recover any losses from these “advance fee” scams, your best defense is to avoid being defrauded in the first place,” FINRA says, and spells out tips for avoiding these sorts of scams.