DUP leader Arlene Foster has told Sky News the Prime Minister's visit to Belfast became "a bit of a distraction" in efforts to restore power-sharing.
Theresa May's direct intervention on Monday had fuelled speculation that an agreement was imminent but Mrs Foster said parties still had "work to do".
When asked why the Prime Minister had travelled to Northern Ireland in those circumstances, the DUP leader laughed before replying: "A very good question and perhaps one you should ask of her.
"Obviously the Prime Minister is always very welcome to this part of the United Kingdom. We did have some conversations yesterday as well and I thought that was useful.
"But in fact, the visit yesterday became a bit of a distraction because we had still work to do and we'll continue to do that work today and in the coming days."
Thirteen months after the power-sharing government collapsed, there were hopes the DUP and Sinn Fein could be close to resolving their differences over an Irish Language Act.
But 24 hours after the Prime Minister's engagement with the two largest parties, the gap between them appeared to be widening.
Mrs Foster said: "When Prime Ministers fly in, there's always a sense that things are moving in a particular direction and we have made good progress.
"But people did jump to certain conclusions. There was talk about a free-standing Irish Language Act…but we won't be agreeing to an Irish Language Act…we've always said that was a step too far."
Sinn Fein negotiator, Conor Murphy MLA, responded: "The talks are at a critical stage and Sinn Fein's focus remains on achieving a deal to restore the political institutions.
"However they want to describe it, the DUP know that the agreement requires an Acht Gaeilge (Irish Language Act).
"The DUP need to make up their mind up whether they are up for a deal or not," Mr Murphy added.
Mrs Foster, whose party has been propping up the minority Tory government at Westminster since last summer, played down talk of a breakthrough coming soon.
"Whether it is this week, whether it is in a couple of weeks or whether it is in a couple of months, what I must ensure is that we have an accommodation that everybody feels content with," she said.