WASHINGTON (Reuters) - President Donald Trump on Tuesday criticized the Federal Communications Commission for not approving Sinclair Broadcast Group Inc’s $3.9 billion acquisition of Tribune Media, calling it “disgraceful” compared with the FCC’s approval several years ago of a deal involving the NBC television network.

The tower of Tribune Broadcasting Los Angeles affiliate KTLA 5 is seen in Hollywood, Los Angeles, California, U.S., July 17, 2018. REUTERS/Lucy Nicholson

“So sad and unfair that the FCC wouldn’t approve the Sinclair Broadcast merger with Tribune. This would have been a great and much needed Conservative voice for and of the People,” Trump said in a post on Twitter.

Trump’s broadside was an unusual attack on a decision of an independent federal agency that makes merger decisions based on whether they in the public interest.

“Liberal Fake News NBC and Comcast gets approved, much bigger, but not Sinclair. Disgraceful!” Trump said in his tweet, referring to the 2011 approval of Comcast Corp’s acquisition of NBC Universal.

Comcast at the time was a provider of video and residential internet service. NBC Universal included the Universal movie studio as well as NBC and other assets.

Sinclair, the largest U.S. local broadcast station owner, won the backing of Trump in a tweet in April but has come under scrutiny by others.

Advocacy group Free Press has said that Sinclair forces stations to “air pro-Trump propaganda” - a charge it denies.

FCC Commissioner Jessica Rosenworcel said on Twitter on Tuesday that she did not agree with Trump’s tweet.

Last week, the Republican-led FCC said it would not approve the acquisition by Sinclair and sent the matter to a hearing before an administrative law, saying that Sinclair would maintain control in practice of some stations it had agreed to divest, even if not in name.

The FCC’s order dealt a serious and potentially fatal blow to Sinclair’s bid to acquire Tribune. Tribune did not immediately comment on Tuesday.

Democrats have attacked FCC Chairman Ajit Pai, whom Trump named to head the agency, for what they claim are a string of decisions benefiting Sinclair and a news media report that Trump’s election campaign struck a deal with Sinclair for favorable coverage.

Pai has repeatedly denied he has taken actions aimed at benefiting Sinclair and said last week he had “serious concerns” about the merger. Sinclair has also denied improper conduct.

Trump last year had suggested that NBC’s licenses could be challenged over its news reporting, something that Pai had rejected.

Pai and an FCC spokesman did not immediately respond to requests for comment on Trump’s tweet. Sinclair and Comcast Corp also did not respond.

The FCC said the administrative judge will review whether Sinclair engaged in misrepresentation or a lack of candor and whether the deal would violate the FCC’s broadcast ownership rules.

Sinclair has denied withholding any information or misleading the FCC.