The U.S. Securities and Exchange Commission published a new warning against initial exchange offerings (IEOs) Tuesday.

According to the notice, IEOs are similar to initial coin offerings (ICOs), many of which the agency has been investigating as unregistered securities offerings over the past several years. While IEO providers may claim their sales are different from ICOs, they may still violate federal securities laws, the SEC said. As such, the agency warned investors to "be cautious" if they are considering investing in an IEO.

"IEOs are being touted as an innovation on ICOs because they are offered directly by online trading platforms on behalf of companies – usually for a fee – to provide immediate trading opportunities for the digital assets," the notice said. "These online trading platforms, which are typically not registered with the SEC and which may improperly refer to themselves as 'exchanges,' may also claim to perform due diligence or other quality assessments of the IEOs."

The SEC warned that a platform saying it is registered does not necessarily mean it actually is registered with the agency, and it emphasized that "there is no such thing as an SEC-approved IEO."