Amazon has emailed a select bunch of third-party sellers who are successful on their platform, warning them that antitrust legislation being considered by Congress could hurt their business.

The email itself refers specifically to "small and medium" businesses, and claims that these could possibly be the ones most affected by the bills, assuming that they are made into law.

According to CNBC, the email reads, in part:

"We're reaching out to a small group of our sellers to make them aware of a package of legislative proposals, currently in Congress, that is aimed at regulating Amazon and other large technology companies."

"It is early in the process and the bills are subject to change, but we are concerned that they could potentially have significant negative effects on small and medium-sized businesses like yours that sell in our store."

The email then asks for interested parties to reach out to set up a phone conversation so that the issue can be discussed in more detail. As of this writing, no information exchanged in one of these phone calls has been made public.

The bills in question are currently all at the markup stage in Congress. Among other things, they would prohibit discrimination against businesses using their services, make data portability schemes mandatory, and put barriers to mergers between the biggest companies in the tech industry.

Especially at issue is one bill, the Ending Platform Monopolies Act, which contains a clause which would make it illegal for Amazon to rank companies higher in search results if they use Fulfillment by Amazon, Amazon's proprietary in-house warehousing and shipping service.

Other antitrust efforts spearheaded by members of Congress will look at issues like censorship and bias on platforms such as Facebook Instagram and YouTube.