John Oliver slammed Sinclair Broadcast Group on Sunday for requiring local anchors to read media-bashing promos.

"Nothing says we value independent media like dozens of reporters forced to repeat the same message over and over again like members of a brainwashed cult," Oliver retorted in a segment about Sinclair. The host of HBO's "Last Week Tonight" previously took on Sinclair last summer. (HBO is owned by CNN's parent company, Time Warner).

Sinclair wrote promos for its network of local broadcasters. The promos describe a "troubling trend of irresponsible, one sided news stories" and claim that "national media outlets are publishing these same fake stories without checking facts first." Sinclair told the stations it must film and run the promos "frequently."

CNNMoney first reported on the promos -- and the tensions they were creating in Sinclair newsrooms -- last month.

Oliver compared the anchors in the promos to hostages, and said one looked like "she'd rather be murdered and set on fire while celebrating her birthday" than read the script.

Related: Sinclair's new media-bashing promos rankle local anchors

The promos, which echo President Trump's anti-media talking points, went viral over the weekend after Deadspin edited dozens of them together to show how anchors across the country were reading the same script.

Related: Sinclair tells stations to air media-bashing promos - and the criticism goes viral

That led Oliver to return to Sinclair on Sunday. His piece last July on the "the most influential media company that you've never heard of" introduced millions of Americans to the network. The segment has more than seven million views on YouTube.

"When you see just how many local stations were forced to read it and you watch them together, as many have been doing online in the last couple of days, you begin to realize the true effect of Sinclair's reach and power," Oliver said Sunday.

Sinclair (SBGI) is the biggest owner of local television stations in the United States, owning or operating 173 of them.

Management's conservative politics have moved down to Sinclair's stations through "must runs" — stories local producers are told to air during their newscasts. The "Terrorism Alert Desk" is a recurring segment. Pro-President Trump commentaries from Boris Epshteyn, a former Trump campaign adviser, are another "must-run" feature.

Oliver highlighted Sinclair's "must runs" Sunday, including a story about the "Deep State," a popular conspiracy theory on the right, allegedly working to undermine President Trump.

Sinclair's political bent has been a factor in its pending acquisition of Tribune Media, which is under review by federal regulators. The deal would add dozens more stations to its portfolio.

-- CNNMoney's Brian Stelter contributed reporting