Urgent talks to avert the collapse of the Northern Ireland power-sharing agreement are set to resume this morning, having continued until 3.30am last night.
Gordon Brown and his Irish counterpart, Brian Cowen, flew into Belfast to chair the talks, which focus on the transfer of policing and justice powers at Hillsborough Castle.
A spokesperson for Downing Street said: "It was hard going but the parties engaged in good faith. There was frank discussion across a range of issues.
"The prime minister and taoiseach [Irish prime minister] remain determined that progress can be made, so discussions will continue on Tuesday morning."
Negotiating teams from the two main parties, DUP and Sinn Fein, are present, as well as representatives of the Ulster Unionists, the SDLP and the Alliance Party.
This comes amidst government anger in London at the Conservative approach to the political crisis in Ulster. Shadow Northern Ireland secretary Owen Paterson convened talks among unionists at an English country estate on the weekend of 16/17 January.
This apparent pro-unionist stance is at odds with the bipartisan approach of the last two decades. The Tories have agreed to field joint candidates with the Ulster Unionist party in Northern Ireland's 18 parliamentary seats.