Politicians have just hours left to reach an agreement on restoring power-sharing in Northern Ireland.
Talks continued until 02:00 BST, with more meetings due later on Thursday morning. The parties have until 16:00 BST to form a new government.
If the deadline is not met, Northern Ireland faces the possibility of direct rule from Westminster.
Sinn Féin and the Democratic Unionist Party are in deadlock over nationalist demands for an Irish language act.
Either the DUP must drop its opposition to a stand-alone act or Sinn Féin must accept a wider form of legislation – a so-called hybrid model which would also cover the Ulster-Scots language.
Round-table talks involving the five main parties and the Irish and British governments were due to take place on Wednesday, but the BBC understands the DUP and Sinn Féin did not show up.
BBC News NI political correspondent Enda McClafferty said the chances of a deal being hammered out were “not good”.
“All the signs and all the vibes from those inside the talks room is that there has been little progress made on the key issue of the establishment of an Irish language act,” he said.
A sitting of the assembly had been scheduled for Thursday at noon which could involve the election of a first and deputy first minister – but only in the event of a deal.
On Wednesday night, the DUP criticised the Irish government for reiterating its support for the establishment of a stand-alone act, which would offer legal protection to the Irish language.
In a statement, the party said: “Only last week the Irish government lectured our United Kingdom government on the importance of observing neutrality when dealing with Northern Ireland parties.
“Yet by publicly declaring its support for Sinn Féin’s position in negotiations, the Irish government has undermined its own credibility as being neutral.”
Earlier, DUP negotiator Edwin Poots said the DUP had respect for language and culture.
“Education and health is a greater priority for me than languages,” he said. “Sinn Féin have identified language as their highest priority. We want to work with them to try to find a way through.”
The party was happy to select ministers on Thursday and continue with negotiations, he added.
Sinn Féin negotiator John O’Dowd called on both the British and Irish governments to intervene and implement what the party says has already been agreed in previous talks.
“The DUP have not moved to address the issues of rights, equality and respect which caused the collapse of the assembly in January,” he said.
‘Profound and serious’
Northern Ireland Secretary of State James Brokenshire flew back from London on Wednesday night – he was needed in the Commons to vote on the Queen’s Speech and for Northern Ireland questions.
He is due back in Westminster on Thursday for further crucial votes.
Mr Brokenshire told the Commons that failure to strike a power-sharing deal would have “profound and serious” implications.
Northern Ireland has effectively been without a devolved government for almost six months.
Its institutions collapsed amid a bitter row between the DUP and Sinn Féin about a botched green energy scheme.
The late deputy first minister, Martin McGuinness, stood down in protest over the DUP’s handling of an investigation into the scandal, in a move that triggered a snap election in March.
A number of attempts to restore power-sharing following that poll foundered, with three deadlines for a deal having already been missed.
Meanwhile at Westminster on Wednesday, the DUP’s 10 MPs helped the Conservative minority government win its first parliamentary vote since the general election.
As part of its arrangement with the Tory party, the DUP backed the government to help it defeat a Labour amendment to the Queen’s Speech, which sets out the government’s plans for the coming year.
The amendment called for an end to cuts in the police and fire services, and called for pay rises for emergency and public service workers.