WASHINGTON (Reuters) - President Donald Trump tweeted his support on Monday for a call by a cable industry group to investigate alleged anti-competitive practices by Comcast Corp, the world’s biggest entertainment company.

The NBC and Comcast logo are displayed on top of 30 Rockefeller Plaza, formerly known as the GE building, in midtown Manhattan in New York July 1, 2015. REUTERS/Brendan McDermid/File Photo

The American Cable Association (ACA), which represents hundreds of smaller cable and broadband providers, on Monday said in a statement that it has asked the Justice Department’s antitrust division to investigate Comcast’s business practices, “focusing on harms stemming from the dominant communications firm’s control of cable systems, TV stations, and regional sports networks concentrated in some of the largest local markets in the country.”

Trump appeared to agree with the industry’ group’s call for a probe, which it said it made to the Justice Department in a Nov. 6 letter.

“American Cable Association has big problems with Comcast. They say that Comcast routinely violates Antitrust Laws,” Trump said on Twitter.

Comcast’s shares dipped following the president’s tweet but quickly recovered most of their losses in a market that was broadly lower. Comcast shares were down about 0.2 percent in late trading.

It is not the first time that Trump has weighed in on regulatory issues related to media companies.

In July, he said the Federal Communications Commission’s decision to reject Sinclair Broadcast Group’s purchase of Tribune Media was “disgraceful.” Two years ago, when Trump was the Republican presidential candidate, he had denounced AT&T Inc’s deal to buy Time Warner Inc, whose businesses included CNN, which Trump has repeatedly attacked.

The ACA said in its call for a probe that with the expiration of requirements that were imposed on Comcast following its 2011 acquisition of NBC Universal, its “ability to raise programming prices in local markets is unmatched by any similar problem created by the AT&T-TW combination.”

The ACA said it was particularly concerned about its members’ access to regional sports networks.

“ACA expects – and there is every reason for DOJ (Justice Department) to expect -- Comcast-NBCU to act on its natural incentives and use its capabilities to harm rivals, unless the government somehow, either through structural or behavioral remedies, deals with them,” the group said in its letter.

Comcast did not respond to the president’s tweet, but said that the ACA letter was “without merit and constitutes an inappropriate attempt to gain leverage in the commercial marketplace.”

“At Comcast NBCUniversal, we are competing in this dynamic environment the way we always have – by continuing to innovate and conducting our business in compliance with antitrust laws and other legal requirements,” the company said in a statement.