Lisa Nandy has said she is "minded to intervene" in the proposed £1.6bn deal for Sky to buy ITV's media and entertainment division.
The culture secretary said there was reasonable grounds to believe the deal could affect free expression in the media and the variety of Britain's news landscape.
Sky said it would "carefully consider" a letter from Nandy and "engage constructively" with the review into the deal.
"We remain confident that bringing Sky and ITV's media and entertainment business together will create a stronger British media," it said.