The Sinn Fein leadership held talks with the Prime Minister in Downing Street yesterday.

Party president Gerry Adams and Deputy First Minister Martin McGuinness are understood to have met Gordon Brown as fears grow of a looming crisis for the Stormont government. A Sinn Fein source confirmed the talks were focused on issues including the devolution of policing and justice powers to the Assembly.

The discussions follow a meeting yesterday between Mr Brown and DUP leader Peter Robinson and his senior party colleague Gregory Campbell.

The DUP denied their talks were linked to the political stand-off with Sinn Fein and said their Downing Street visit was routine.

The two parties are split on a series of issues including the transfer of policing powers, education reform, an Irish Language Act and the future of the Maze prison site.

Sinn Fein is demanding the transfer of policing control to the Assembly.

It is also calling for the introduction of legislation protecting the Irish language, which it insists are commitments in the St Andrews Agreement that paved the way for devolution in Northern Ireland.