Parties in Northern Ireland have a "short few weeks" to strike a deal to save powersharing at Stormont, Northern Ireland Secretary of State James Brokenshire said.
With a deadline for forming a new ruling executive following this month's snap election having elapsed at 4pm without agreement, the British government now either has to call yet another poll or potentially reintroduce direct rule from Westminster.
Mr Brokenshire indicated he will delay taking action to allow the North's political leaders some more time to resolve their differences.
Without an executive or agreed budget for the upcoming financial year, control of Stormont's finances will be handed to a senior civil servant on Wednesday, albeit subject to tight spending constraints.
Mr Brokenshire said that was "not sustainable", making clear the final window for negotiations would not be allowed to drift.
"I think there are a short few weeks in order to resolve matters," he said.
Northern Ireland Secretary James Brokenshire says there is an overwhelming desire for strong and stable devolved government pic.twitter.com/KaRkoiMYpv— RTÉ News (@rtenews) March 27, 2017
"The reason I say that is because of the stark issue in relation to public services here in Northern Ireland and the lack of a budget having been set, and therefore it is the impact on public services on having an extended period that is very much at the forefront of my mind in terms of the responsibilities that we have as the UK government to provide that assurance to the public here."
The Democratic Unionist Party/Sinn Féin administration collapsed in January amid a bitter row over a botched green energy scheme. The subsequent snap election campaign laid bare a range of other contentious issues dividing the parties.
Mr Brokenshire rejected criticism of the British government's handling of the talks to form a new executive and defended the fact Prime Minister Theresa May did not participate in the process.
He said the government had played a "positive and active" role and Mrs May had been kept updated throughout.
He declined to be drawn on calls for an independent mediator to be appointed to inject fresh impetus to negotiations that some politicians have described as a "shambles" to date.
Under current legislation, the government is required to call another snap election if a deadline for forming an executive passes.
However, there is some room for manoeuvre, as there is no obligation to set a poll date immediately, rather within a "reasonable period".
Making a public statement at Stormont House, Belfast, after the 4pm deadline passed, Mr Brokenshire said there was "no appetite" for an immediate election.
The government could also theoretically reintroduce direct rule, but that move - which would require emergency legislation - looks unlikely at this stage at least.
Mr Brokenshire said there was "an overwhelming desire" among politicians and the public for "strong and stable devolved government".
"We now have a short window of opportunity to resolve outstanding issues and for an executive to be formed," he said.
"Everyone owes it to the people of Northern Ireland to grasp that and provide the political leadership and stability that they want."
Mr Brokenshire said he would make a full statement in the House of Commons tomorrow setting out a way forward for the region.
Flanagan warns of Brexit dangers
Minister for Foreign Affairs Charlie Flanagan said the context of Brexit made it all the more imperative that a new executive was formed as soon as possible.
"The absence of agreement on the establishment of an executive is, for many reasons, deeply regrettable," he said.
"However, it is particularly concerning that a vacuum in devolved government in Northern Ireland should now be occurring just as the island of Ireland faces up to the many serious challenges represented by the UK exit from the EU.
"In these circumstances, all concerned must redouble efforts to achieve the re-establishment of power-sharing government in Northern Ireland, which is so plainly in the interests of all its citizens.
"The Irish Government will continue to advocate very strongly for Northern Ireland's interests to be protected.
"However, there is no substitute for an executive speaking with one voice on these critical issues."
Sinn Féin and the Democratic Unionists have blamed each other for the breakdown of the talks.
DUP leader Arlene Foster claimed Sinn Féin's "inflexible" approach to negotiations was to blame.
She said she did not believe another election would solve anything.
Sinn Féin leader in Northern Ireland Michelle O'Neill, however, claimed the DUP had failed to live up to previous agreements and was standing in the way of progressive policies.
"We are standing firm - previous agreements need to be implemented," she said.
"We came at the negotiations with the right attitude, wanting to make the institutions work, wanting to deliver for all citizens.
"Unfortunately, the DUP maintained their position in relation to blocking equality, delivery of equality for citizens, that was the problem."
Sinn Féin has said it will not share power with Mrs Foster as first minister until a public inquiry into the renewable heat incentive (RHI) is concluded.