GERMANY — Comcast Corp. isn’t the only U.S. internet service provider throttling the bandwidth of high-volume users, according to the results of a German study obtained by The Associated Press this week.Cox Communications employs the practice, too, and nearly as egregiously.

According to the study, performed by the Max Planck Institute for Software Systems in Saarbruecken, Germany, Comcast blocked the connections of 491 subscribers who were part of the study. That’s 62-percent of the 788 Comcast users who were part of a worldwide sample of 8,175 connections examined.

Cox blocked 82 of 151 subscribers, or 54-percent, the study indicated.

Only one other ISP in the world was found to block subscribers: StarHub, which is Singapore’s dominant cable company.

Philadelphia-based Comcast and Atlanta-based Cox are the second- and fourth-largest ISPs in the U.S., respectively.

Comcast became the subject of a Federal Communications Commission investigation earlier this year after subscribers and competitors complained the company was limiting the bandwidth of users who engage in behaviors like online file-sharing and downloading massive amounts of music and video. Comcast maintains the tactic is reasonable and necessary “traffic management” to ensure bandwidth is available to all users.

In their complaints, consumers alleged Comcast didn’t warn them before limiting or shutting off what they thought were unlimited connections. Cox has acknowledged at least since 2006 that it engages in “protocol filtering” to manage traffic on its network, according to the AP. However, Cox denies the practice is discriminatory in any way.

The Planck study found what the AP called “authoritative” evidence Comcast blocks BitTorrent transfers, despite Comcast’s denial that it treats some types of traffic different than others.

The Planck study found no evidence of traffic interference by phone-company ISPs, the AP noted.