Update 7pm: The North's two main parties remain locked in talks at Stormont with the latest deadline to restore powersharing due to expire within a matter of hours.
Sinn Féin has said the talks are continuing but no agreement has yet been reached with the DUP.
Northern Ireland Secretary of State James Brokenshire has warned both parties that unless there is a breakthrough before the end of Monday the only option remaining would be to legislate for a budget for the region at Westminster.
Sinn Féin's Gerry Adams, Mary Lou McDonald and Pearse Doherty have joined the party's negotiating team in Belfast.
Both James Brokenshire and Foreign Affairs Minister Simon Coveney have been holding meetings with the parties throughout the day.
The DUP, Sinn Féin and the Irish and UK Governments have been remaining tight lipped about any progress.
The region's smaller parties held a meeting earlier in the day to discuss the lack of openness and transparency in the talks negotiations.
The executive collapsed in January and the North has been without a power-sharing government since then.
Despite endless rounds of discussions, a deal to restore devolution has proved elusive with the introduction of an Irish language act seen as the main issue.
Northern Ireland is inching towards direct rule from Westminster after the Democratic Unionist Party (DUP) called on the Secretary of State to set a budget for the region.
The DUP made the call just hours before the latest deadline to restore powersharing at Stormont runs out.
Sinn Fein, however, has said a deal could still be done, but insisted it must be "a deal for all in society and not just for the political leaderships of unionism".
The parties have been warned they must reach agreement by the end of Monday or Northern Ireland Secretary of State James Brokenshire will be forced to introduce a budget via Westminster.
Talks between the DUP and Sinn Fein paused on Friday for the weekend, without an agreement being reached.
On Monday morning, ahead of the resumption of talks, the DUP called on Mr Brokenshire to set a budget to ensure a "measure of good government" in the region.
The party said it would not accept "a bad agreement cobbled together to suddenly suit the timetables of others".
"Our position has not changed, we want to see an executive set up - we would have done it in March and sorted these issues in tandem," said the party in a statement.
"Given Sinn Fein have dragged their feet over the last 10 months, the secretary of state should bring forward a budget to bring a measure of good government to Northern Ireland," the statement added.
The DUP said it would continue the discussions as it believes "devolution is best for Northern Ireland".
But it warned that it would not be a part of a "bad agreement cobbled together to suddenly suit the timetables of others".
Sinn Fein’s Conor Murphy said while he believed a deal could still be done, it "needs to be a deal for all in our society and not just for the political leaderships of unionism".
"If the political institutions are to be sustainable then they must be restored on the basis of equality, rights and respect.
"That requires an end to the DUP’s denial of rights citizens enjoy everywhere else on these islands, language rights, marriage rights and the right to a coroner’s court," Mr Murphy added.
Earlier, SDLP leader Colum Eastwood said that if a deal was not reached by Monday’s deadline, his party would not accept direct rule from Westminster but only joint rule from both London and Dublin.
He said: "As I set out in January this year, I want to again make clear that a return to direct rule from London is wholly unacceptable.
"It would be a significant and serious breach of our political accommodation in the North and therefore must not be the automatic and the only fall-back option."
Mr Eastwood added: "In the absence of an Executive and Assembly, giving representation to the North’s two traditions falls on both the Irish and British Governments.
"Maintaining that balance means that the alternative to direct rule is the joint stewardship of the North by the two governments."
The executive collapsed in January and Northern Ireland has been without a powersharing government since then.
Despite endless rounds of discussions, a deal to restore devolution has proved elusive, with the introduction of an Irish language act seen as the main issue.
Ireland’s Foreign Affairs Minister Simon Coveney has arrived in Belfast in a bid to help the parties reach a deal.
In a tweet, he said this was an important day for Northern Ireland, and added that "with political will and a willingness to work together on all sides there is a deal to be done ".
Prime Minister Theresa May’s official spokesman said: "The talks are still ongoing. We are still working with the parties on reaching an agreement.
"We have had progress but there are still significant gaps which remain and we continue to work with them to overcome these.
"You can expect James Brokenshire to update Parliament later this week on how that is progressing.
"We continue to work with the parties on trying to overcome the differences between them and to restore devolved government, which is in the interests of all communities in Northern Ireland."
He added: "We are clear we don’t want to see a return to direct rule, we want a return of devolved government in Northern Ireland, so that local decisions can be made by local politicians.
"James Brokenshire has been clear that the latest we can practically introduce legislation to enable the executive’s formation would be this week in order for it to be in time for a new executive to set a budget."
"All political parties have a responsibility to act thoroughly and properly where instances of unacceptable behaviour come to light, and to take appropriate action," said Ms Butler, who called for all parties to publish their complaints procedures.