Comcast has begun imposing a fee on Internet middleman Level 3 Communications, one of the companies that Netflix has hired to deliver movies and TV shows to Web customers.

Comcast, the largest U.S. cable TV company, has set up an Internet “toll booth,” charging Level 3 whenever customers request content, the Broomfield, Colorado-based company said in a statement yesterday.

Level 3 plans to complain to U.S. regulators who may enact so-called net-neutrality rules next month. The Federal Communications Commission is seeking to bar phone and cable providers from interfering with legal traffic on their networks. The rules are backed by President Barack Obama and companies led by Google, EBay and IAC/InterActiveCorp. Phone and cable companies say rules aren’t needed and may hurt investment.

“This action by Comcast threatens the open Internet and is a clear abuse of the dominant control that Comcast exerts in broadband access,” Thomas Stortz, Level 3’s chief legal officer, said in the statement. “With this action, Comcast is preventing competing content from ever being delivered to Comcast’s subscribers at all, unless Comcast’s unilaterally determined toll is paid.”

Comcast, which is seeking regulatory approval to acquire majority ownership of NBC Universal, defended the fee in a statement, saying it is based on “long established and mutually acceptable commercial arrangements” with Level 3’s peers…

FCC Chairman Julius Genachowski, in proposing net neutrality rules last year, called for a principle of non- discrimination by Internet-service providers. The FCC will meet on Dec. 21.

“This means they cannot block or degrade lawful traffic over their networks,” Genachowski said.

And, btw, putting a surcharge, a toll on your traffic is the same as blocking traffic. If you don’t pay the toll, your traffic doesn’t go through – or Comcast will slow it down enough to make it unwatchable.

Throughout most of the United States, Comcast has been working their semi-competent buns off installing throttling mechanisms. They told everyone – including the Feds – this was to protect consumers from the exorbitant demands of nerds and illegal downloads. Shock and amazement! It’s just of an accident of nature that it can be used as a weapon to extract tolls from companies using the Web for business purposes.