The Democratic Unionist Party accused Sinn Féin of frustrating the work of the Executive after disagreements over issues like abolishing selection for post-primary education and devolving policing and justice powers to the Assembly.
However, Sinn Féin said it was prepared to meet unionists at any time to resolve outstanding matters.
The SDLP leader, Mark Durkan, said the political stand-off was creating a crisis at the heart of government and said the Assembly may need to be recalled from its summer recess.
