Sinn Féin Vice President Mary Lou McDonald TD has said the British and Irish governments must live up to their responsibilities to the peace process.
Speaking ahead of an event at Westminster where she will brief British MPs, Ms McDonald said;
"Sinn Féín demonstrated very clearly during the Haass negotiations our seriousness and determination to find a way forward.
"We made compromises during those talks. For any process aimed at resolving these issues to succeed unionist political leaders need to show a similar willingness. That has not been evident so far.
"Despite this there does exist a window of opportunity to resolve the difficult issues of flags, parades and the past.
"Party leaders in the Assembly have agreed an intensive round of talks starting this week and Sinn Féin is engaging positively in this process.
"However key to this is that the British and Irish governments – the co-guarantors of the Agreement – need to up their game.
"Tomorrow myself, Gerry Adams and Martin McGuinness will be meeting David Cameron and we will be giving him a clear message that the British government – and the Irish government – must become far more engaged in upholding and fulfilling their obligations.
"There is a responsibility on all political leaders in Britain and others in civic society, in particular in the Irish diaspora community, in the trade unions and across the political and social spectrum to join us in ensuring the peace process continues to be driven forward positively.”