Donald Trump has warned of potential competition problems over Netflix’s $83bn (£62bn) deal to buy Warner Brothers’ movie studio and streaming networks.

The US president, speaking at an event in Washington DC on Sunday, confirmed he would be involved in deciding whether the government approved the takeover.

He said Netflix had a “big market share” and the companies’ combined size “could be a problem”.

Netflix emerged as the winner of the Warner Bros Discovery auction on Friday, beating rivals Paramount Skydance and Comcast.

There are concerns that combining Warner’s HBO Max streaming service with Netflix could put the company over the 30% market share threshold in the US.

However, it is understood that Netflix disputes this figure. It is expected to argue that other streaming services such as YouTube should also be considered in the media landscape.

Netflix accounts for 8% of total TV viewing time in the US, according to the research firm Nielsen, putting it behind the likes of YouTube, Disney and Paramount.

The Warner Brothers deal would give Netflix control of the studio behind franchises including Harry Potter, Batman and Superman, as well as HBO, home to shows including Game of Thrones, The White Lotus and Succession.

At an event at the John F Kennedy Center in the US capital, Trump said Netflix had a “very big market share” that would “go up by a lot” if the deal went ahead.

Many industry voices, including Hollywood unions, have argued the deal should be blocked.

The Netflix-Warner merger is not expected to be completed until the third quarter of 2026 or later, and will be subject to regulatory approval in the US and in Europe. It is also expected to be reviewed by the Department of Justice.

Trump said Netflix’s co-chief executive Ted Sarandos visited the Oval Office recently, and praised him for his work at the company. “I have a lot of respect for him. He’s a great person,” the president said. “He’s done one of the greatest jobs in the history of movies.”

Before the deal, reports suggested that Trump preferred Paramount to win the Warner Brothers takeover because it is backed by Larry Ellison, the billionaire co-founder of the tech company Oracle and a Trump supporter. Paramount Skydance’s chief executive is Ellison’s son, David.

William Kovacic, the former chair of the Federal Trade Competition, the US competition regulator, said the president’s involvement in such a deal would be “unprecedented”.

He told BBC Radio 4’s Today programme: “The negotiation of any possible solution is going to run through the White House, and that means we’re going to have probably a deep level – an unprecedented level – of presidential control in the resolution of what used to be a technical analysis of a merger.”

Blair Westlake, the former chair of Universal Studios Television and Networks, said it was natural that big media companies were consolidating.

“A lot of people don’t realise that the No 1 place that consumers in the world go for viewing of content is YouTube,” he told the Today programme. “It is far and away beyond anything else.”

Dan Coatsworth, the head of markets at AJ Bell, said: “Fundamentally, Trump wants to bring some pizzazz back to Hollywood. He wants to resurrect the glitz and glamour of the US film industry, whose star has faded as more productions are made overseas, thanks to tax incentives and cheaper costs.

“Netflix will be under pressure to do as much as possible on home soil, so any commitment to do a certain amount of production in the US could help to win Trump over.”

Netflix declined to comment.