Rob Bonta, California’s attorney general, said his office will investigate a possible merger between Paramount Skydance and Warner Bros Discovery, hours after Netflix backed away from a planned takeover.

“Paramount/Warner Bros is not a done deal,” Bonta said in a post on X. “These two Hollywood titans have not cleared regulatory scrutiny — the California Department of Justice has an open investigation, and we intend to be vigorous in our review.”

Any acquisition of Warner Bros would require approval from regulators in the United States and Europe, including the US justice department’s antitrust division. The deal Paramount struck for Warner is valued at nearly $111bn.

The merger poses a risk for California’s economy. Paramount’s bid is likely to raise concerns about job cuts in the state, which also dogged Netflix’s bid. Paramount sees $6bn in cost “synergies” in the deal, which typically means massive layoffs, reducing the number of suppliers, squeezing existing contractors for better terms after the two companies merge or other reductions.

The chief executive of Paramount, David Ellison, said his company was pleased the Warner Bros board had “unanimously affirmed the superior value of our offer”, which he said delivered “WBD shareholders superior value, certainty and speed to closing”. Ellison is the son of Oracle co-founder Larry Ellison, a close ally of Donald Trump.

On Friday, Warner Bros Discovery reportedly agreed to be acquired by Paramount Skydance. Reuters and Deadline reported that the deal was announced in a global town hall by the company. Paramount and Warner Bros did not immediately confirm the deal to the Guardian.

A merger between the two media giants is also facing backlash from several lawmakers. Senator Elizabeth Warren, a key voice against growing monopolies, echoed Bonta’s concerns after Netflix walked away from the deal on Thursday, and noted that Netflix CEO Ted Sarandos was seen at the White House shortly before the company said it would bow out of the deal.

“A Paramount Skydance-Warner Bros merger is an antitrust disaster threatening higher prices and fewer choices for American families,” Warren said in a statement. “What did Trump officials tell the Netflix CEO today at the White House? A handful of Trump-aligned billionaires are trying to seize control of what you watch and charge you whatever price they want.”

The senator added: “With the cloud of corruption looming over Trump’s Department of Justice, it’ll be up to the American people to speak up and state attorneys general to enforce the law.”

On Friday, Bonta responded to concerns about the merger posted by actor Mark Ruffalo.

“Please let’s circle up all the State AG’s and talk about how this is going to kill completion in the industry and drive down wages, and product quality for consumers,” Ruffalo posted.

“There are lots of agents in Hollywood who can tell you how past mergers and consolidations have hurt their clients and business. There is lots of talent that can tell you the same.”

Bonta reposted the actor’s comments, responding that he is in “conversation with my AG colleagues about Paramount/Warner Bros”.

The California department of justice did not immediately respond to a request for comment from the Guardian.

The Writers Guild of America, the union representing thousands of television and film writers along with other media workers, has said a Paramount takeover of Warner Bros would hurt jobs.

Warner Bros canceled $2bn in content after merging with Discovery in 2022, and Paramount’s recent merger with Skydance led to 1,000 layoffs, the union said in written testimony to the US Senate.